DENTITION OF THE GREAT WHITE SHARK, CARCHARODON CARCHARIAS WITH COMPARISONS TO ISURUS AND LAMNA
(LAMNIFORMES: LAMNIDAE)
A Thesis Presented to the Faculty of the Graduate School
of Cornell University In Partial Fulfillment of the Requirements for the Degree of
Master of Science
by Joshua Kent Moyer
January 2014

© 2014 Joshua K. Moyer

ABSTRACT This study describes tooth structure, development and replacement in the great white shark, Carcharodon carcharias. Microstructure of the osteodont condition, characteristic of Lamnidae, differs from the orthodont condition found in sharks such as Carcharhinidae. Osteodentine development in Carcharodon is described. Findings are applied to identify shark teeth recovered in an archeological investigation. Differences in development between so-called lateral cusplets in the teeth of Carcharodon and lateral cusplets of Lamna are described. These structures are not homologous and the so-called lateral cusplets of Carcharodon are interpreted as serrational cusplets. Use of dental characters in lamniform phylogeny is reviewed, and problems in character definition and coding from earlier analyses are identified. When those problems are corrected – and especially in view of the finding that serrational cusplets of Carcharodon are not homologous to lateral cusplets in other Lamniformes – I conclude that Lamna is the sister group to Isurus + Carcharodon.

BIOGRAPHICAL SKETCH Joshua Moyer was born on October 16, 1987 and grew up in southeastern Pennsylvania with his parents, younger sister, and family dog, all of whom he loves dearly. He developed an interest in marine biology that became a passion at an early age. Supportive parents and mentors helped Joshua throughout his childhood and adolescence to develop his passion. Joshua attended Millersville University of Pennsylvania, where he earned his Bachelor of Science in Biology with Departmental Honors under the tutelage of Dr. Dominique Didier. In Joshua’s junior year of college, Dr. Didier introduced him to Dr. Willy Bemis. After working with Dr. Bemis at Shoals Marine Laboratory as a teaching assistant and then instructor in Dr. Bemis’ shark biology course, Joshua moved to Ithaca, New York where he began work with Dr. Bemis that would become Joshua’s Master of Science thesis. Joshua intends to continue his education through training both inside and outside the lab and classroom. In so doing, he will continue to nurture his appreciation for and awe of the natural world around him and eagerly awaits the opportunities to share his enthusiasm, adventures, and lessons learned with others.
iii

I respectfully dedicate this work to my family, friends, and mentors. iv

ACKNOWLEDGMENTS Barbara Brown (AMNH), Karsten Hartel and Andy Williston (MCZ), Gordon Hubbell (Jaws International), John Lundberg (ANSP), Lisa Natanson (NMFS), Irvy Quitmyer (FLMNH), Rob Robbins (FLMNH), Mark McGrouther and Amanda Hay (AMS) and Jeff Johnson (QM) allowed me to study specimens in their collections. Andrew Stewart and Kate Murphy (MNZ) helped us find and study photographs of MNZ P.052022. John Friel and Charles Dardia (CUMV) facilitated access to specimens and helped manage inter-institutional loans of specimens. John Friel’s service as a member of my graduate committee and his comments on this manuscript were much appreciated. Harry Greene also served on my committee and was a source of support and valuable feedback. Mark Riccio and Fred von Stein provided help with scanning at the Biotechnology Resource Center Imaging Facility (Cornell University). Margret S. Thompson and Patricia Homer Reynolds provided CT scanning at the Cornell University College of Veterinary Medicine. Françoise Vermeylen, Cornell Statistical Consulting Unit, helped to design mixed models for statistical analyses.
v

TABLE OF CONTENTS Biographical Sketch......................................................................................................iii Acknowledgments .........................................................................................................v Table of Contents .........................................................................................................vi Introduction ...................................................................................................................1 Methods and Materials ................................................................................................11
Institutional Abbreviations ..............................................................................11 Materials Examined.........................................................................................11 Annotated Anatomical Abbreviations .............................................................14 Measurements .................................................................................................. 16 Photographs and Illustrations ..........................................................................19 Results .........................................................................................................................19 Sizes of Specimens Examined.........................................................................19 General Description of Jaws and Dentition.....................................................20 Numerical Analyses of Teeth and Dentition ...................................................23 Descriptions of Teeth ......................................................................................26 Tooth Development, Replacement, and Histology..........................................28 Lateral Cusplets, Serrational Cusplets, and Variations in Lamnids ................33 Identification of teeth from an archaeological dig at Smuttynose Island ........34 Discussion.................................................................................................................... 35 Tooth Characters and Phylogenetic Interpretations of Lamnidae ...................36 Dental Formulae and Variation in Tooth Shape in Lamnidae.........................41 Tooth Size and Total Length Estimates...........................................................44 Tooth Histotypes .............................................................................................45 Summary and Remarks on Future Studies ......................................................47 References ...................................................................................................................50
vi

Figure List and Captions .............................................................................................62 Tables Figures
vii

Introduction Studies of teeth play important roles in understanding elasmobranch evolution,
ecology and behavior. Scientific and popular literature irrevocably links the great white shark, Carcharodon carcharias, to its teeth, yet many details of its teeth and dentition remain unknown. Great white sharks, like other elasmobranchs, have a polyphyodont dentition in which multiple generations of replacement teeth develop and are shed, a condition termed lyodonty (= loose tooth; Smith and Coates, 1998). Tooth replacement begins in embryos and continues throughout life, yielding thousands of individual teeth and contributing to what Applegate and EspinosaArrubarrena (1996) called an “excellent fossil record, consisting almost entirely of teeth.” Some relatively complete fossils are known, including an exceptionally preserved specimen from the early Pliocene of Peru (Ehret et al., 2009).
Lamnidae includes three extant genera and five species, which are the porbeagle (Lamna nasus), salmon shark (L. ditropus), shortfin mako (Isurus oxyrhinchus), longfin mako (I. paucus), and great white shark (Carcharodon carcharias). Figure 1 shows their phylogenetic relationships based on anatomical and molecular phylogenetic work of Naylor et al. (1997) who found that Carcharodon is the sister taxon of the two species of Isurus. Using data sets of anatomical characters including dental characters, Long and Waggoner (1996) and Shimada (2005) found that Carcharodon is the sister taxon to the two species of Lamna. We comment on these characters and analyses in the Discussion.
Teeth of extant subadult and adult great white sharks have prominent serrations on the mesial and distal edges of the crown. The upper, or palatoquadrate, teeth are
1

broad, triangular, and lingo-labially flattened. The lower, or Meckelian, teeth are narrower and more finely serrated. This dentition is well suited for feeding on large mammals such as pinnipeds (Klimley et al., 1996; Long et al., 1996; Motta and Huber, 2012).
In contrast to subadults and adults, juvenile great white sharks feed mainly on teleosts and smaller elasmobranchs (Long and Jones, 1996). This ontogenetic difference in diet correlates with ontogenetic changes in tooth morphology. Anticipating a major finding of this project detailed in the Results section, we refer to structures formerly known as lateral cusplets in juvenile great white sharks as serrational cusplets because they are not homologous to the lateral cusplets of Lamna or more basal lamniforms such as Odontaspis and Carcharias. Teeth of juvenile great white sharks have conspicuous serrational cusplets on either side of the central crown. The lower jaw teeth of juvenile great white sharks resemble those of piscivorous sand tigers (Odontaspis and Carcharias; Applegate, 1965) and mako sharks, Isurus oxyrinchus and I. paucus (Ebert, 2003; Castro, 2011) in having long, narrow cusps. The juvenile tooth morphology occurs in great white sharks < 1.5 m TL (Hubbell, 1996; Motta and Huber, 2012). The transition to the broader triangular adult teeth is an example of ontogenetic heterodonty, a type of heterodonty described for the carcharhinid Hemitriakis by Compagno (1970) and in Heterodontus by Reif (1976, 1984).
Many workers describe shark teeth in terms of functions such as “crushing teeth”, “tearing teeth”, or “piercing teeth” (Peyer, 1968; Budker, 1971; Reif, 1976; Cappetta, 1987, 2012; Frazzetta, 1988; Motta and Huber, 2012). Diet and food
2

processing are not the sole selective forces on tooth shape, for some sharks use teeth in mating (Stevens, 1974) and the homodont teeth of some myliobatid rays function differentially depending on their location in the mouth (Motta and Huber, 2012). Feeding ecology and tooth morphology thus may not be as directly related as often assumed (Whitenack, 2008). Additionally, one of the best-studied sharks, Squalus acanthias, has a homodont dentition, leading to the misconception that few shark species exhibit differences in tooth morphology within a single jaw. Such differences in tooth morphology along the length of the jaw are termed monognathic heterodonty (Applegate, 1965; Reif, 1976; Compagno, 1988). Bullhead sharks such as Heterodontus portusjacksoni offer classic examples of monognathic heterodonty, with the adult dentition consisting of piercing teeth in the front of the jaw and crushing teeth posteriorly (Reif, 1976, 1984). The great white shark exhibits what Compagno (1988) referred to as gradient monognathic heterodonty, in which variations in tooth shape occur gradually along the length of the jaw. While not as striking as the obviously differentiated teeth of Heterodontus, proportional changes in tooth shapes are evident in Carcharodon carcharias although until now they have not been the subject of detailed morphometric study.
The term “tooth row” has been used to describe two different aspects of elasmobranch dentitions. Here, we limit our use of the term tooth row to mesial to distal series of teeth arranged side by side along the jaw, with each tooth in a row at approximately the same developmental stage (Mollet and Bourdon, 1998; a synonym is “tooth series,” e.g., Long and Waggoner, 1996). A shark jaw has many rows of teeth, because each functional tooth has replacement teeth lingual to it, and each
3

replacement tooth and replacement teeth flanking it make up a row of teeth. Some workers also use the term “tooth row” for developmental sequences of replacement teeth consisting of an erupted functional tooth and the teeth in various stages of development lingual to it (e.g., Shimada, 2002a; Ebert et al., 2013: Fig. 18.). For clarity, we refer to such a developmental sequence of teeth as a tooth file (Mollet and Bourdon, 1998; a synonym term is “tooth family,” e.g., Reif, 1984). Thus, a tooth row consists of individual teeth from many tooth files whereas a tooth file consists of individual teeth that each belongs to a separate row.
Conceptually related to tooth rows and tooth files is the term tooth locus (Bemis et al., 2005; also known as a “tooth position,” e.g., Shimada, 2005: Fig. 5). A tooth locus is the position along the jaw at which a particular tooth file occurs. There are as many tooth loci in a jaw as there are teeth in a row. But there is only one set of loci, whereas there are as many rows as there are teeth in a tooth file.
Identifying sharks to species based on a single tooth requires an understanding of the entire dentition of a species. Few groups have been studied in adequate detail, but one example is Carcharhinidae (Naylor and Marcus, 1994). The ability to refer an isolated shark tooth to a species is obviously valuable in many contexts, such as archaeology.
Just as mammalian tooth formulae are a part of diagnoses at various taxonomic levels, some workers use dental formulae to describe the arrangement of teeth within shark jaws. General dental formulae give only the number of functional teeth in each jaw quadrant without identifying tooth types or homologies of particular tooth loci. Species accounts commonly include such formulae. For example, Bigelow and
4

Schroeder (1948: 127) give the following general dental formula for the shortfin

mako, Isurus oxyrinchus

12 or 13 — 12 or 13 12 or 13 — 12 or 13

where the long dashes represent the palatoquadrate and mandibular symphyses. Thus,

a shortfin mako has 12 or 13 teeth in each of the four quadrants of the jaws. Castro

(2011) provides similar descriptions for this species, but in the text and not as a

formula. Bigelow and Schroeder (1948: 137) give the tooth formula for Carcharodon

carcharias in a slightly different format, which we have rearranged here:

13 — 13 11 or 12 — 11 or 12

A more interpretive approach to dental formulae specifies both the types and

number of teeth (e.g., Applegate, 1965; Applegate and Espinosa-Arrubarrena, 1996;

Long and Waggoner, 1996; Shimada, 2002a). Such formulae rely on concepts of

homology for tooth loci along the tooth row. Several studies examine homologies of

tooth loci within Lamniformes, however, there is remarkably little agreement about

the homologies of specific tooth loci. In particular, there are different interpretations

for recognizing homologous tooth loci in Carcharodon. Reproduced in Figure 2 is an

illustration from Applegate and Espinosa-Arrubarrena (1996: Fig. 1a; note that some

aspects of this terminology derive from Leriche, 1905). They recognize four types of

teeth in the upper jaw (anteriors, intermediate, laterals and posteriors) and three types

of teeth in the lower jaw (anteriors, laterals and posteriors). Thus, their dental formula

for Carcharodon carcharias is:

A2 I1 A3

L4-7 P3-4 L4-7 P3-4

5

This formula means that there are two anterior teeth in the upper jaw, followed by one intermediate tooth, followed by four to seven lateral teeth and three to four posterior teeth. In the lower jaw, there are three anterior teeth, four to seven lateral teeth, and three to four posterior teeth. Note that this dental formula assumes that we can reliably differentiate four types of teeth in the upper jaw and three types of teeth in the lower jaw. Also note in Figure 2 that Applegate and Espinosa-Arrubarrena (1996) indicate the first two teeth in the upper jaw as I and III. Their use of Roman numerals modifies Applegate’s (1965) use of letters to refer to specific anterior teeth. Although the tooth indicated as III is one of only two anterior teeth in the palatoquadrate, Applegate and Espinosa-Arrubarrena (1996) state that it corresponds to the third upper position (III) based on comparisons to other lamniforms. No further explanation of this supposed homology is given, and no other workers seem to have accepted this interpretation.
Shimada (2002a; 2005) focused on identifying interspecific dental homologies within macrophagous Lamniformes (the two species of microphagous Lamniformes, Cetorhinus maximus and Megachasma pelagios, have hundreds of small teeth, making it impossible to recognize specific positional homologies to the teeth typical of other Lamniformes). Shimada based homologies primarily on the positions of the teeth within the jaws. Figure 3 compares tooth homologies in the five extant species of Lamnidae based on Shimada (2005: Fig. 4). Shimada recognizes intermediate teeth in both the upper and lower jaw and does not identify posterior teeth in Isurus or Carcharodon (Fig. 3). Thus, the dental formula for Carcharodon according to Shimada’s (2005) scheme is:
6

A2 I1 L10 A2 I1 L9

In yet a third different interpretations of tooth homologies in the great white

shark, Long and Waggoner (1996) report the following formula:

A2 I1 A2

L5 P5 L5 P5

Note that, like Applegate and Espinosa-Arrubarrena (1996), this formula does not

recognize an intermediate tooth in the lower jaw. Long and Waggoner (1996:

character 4) interpret that there is a diastema, or gap, between the intermediate tooth

and first lateral tooth in Carcharias taurus and Isurus oxyrinchus but not in

Carcharodon.

Landolt (1947) and Peyer (1968) describe and illustrate aspects of tooth

development and replacement for the great white shark, but many details remain

unknown. Most histological studies of tooth development concern embryos, juveniles

or smaller species, such as lamniform embryos (Shimada, 2002b), Lamna (Purdy and

Francis, 2007), Ginglymostoma cirratum (Reif et al., 1978; Luer et al., 1990),

Negaprion brevirostris (Moss, 1967), Mustelus canis (Moss, 1972), Carcharhinus

falciformis (as C. menisorrah; Kemp and Park, 1974), and Triakis semifasciata (Reif

et al., 1978). Grady (1970), Reif (1976, 1984), Kemp (1999), Sawada (2003) and

Sawada and Inoue (2003) summarize aspects of the process. Embryonic development

of teeth begins with an infolding of ectoderm termed the dental lamina (Fig. 4A-C).

New tooth buds initially develop at the inner end of the dental lamina, here indicated

as primordial tissue (Fig. 4A-D). Interactions between the dental lamina and

underlying mesenchyme result in formation of a dental papilla, which together with

7

the dental lamina constitute a tooth bud. Once a tooth bud is formed, subsequent tooth development and transport occurs in a lingual to labial direction (Fig. 4D). Progressively, the tooth buds enlarge and undergo successive stages of mineralization to form functional teeth (Fig 4D). The dental lamina differentiates to form ameloblasts, whereas the dental papilla gives rise to odontoblasts. Extracellular enameloid matrix accumulates between the dentine-forming odontoblasts and the enamel-forming ameloblasts. It mineralizes to become the enameloid cap of the tooth (Fig. 4). Subsequently, dentine fills the enameloid cap.
Extant elasmobranchs have two basic type of dentine, here termed orthodentine and osteodentine. Orthodentine is similar to the dentine of human teeth, in which long odontoblasts processes extend into mineralized dentine. Osteodentine, in contrast, resembles spongy bone in which dentine cells surround a trabecular arrangement of vascular canals. The distribution within teeth and relative contribution of orthodentine and osteodentine to the teeth differ phylogenetically within elasmobranchs. In broad terms, elasmobranchs have two histotypes referred to as orthodont and osteodont (Glikman, 1967). Orthodont teeth have a prominent pulp cavity surrounded by orthodentine, best known in carcharhinid sharks (Compagno, 1988). Zangerl (1981) believed orthodont teeth to be the plesiomorphic histotype for sharks. Fully developed osteodont teeth, such as those of the great white shark, lack a pulp cavity because the bone-like osteodentine progressively fills the pulp cavity as the tooth develops (Bertin, 1958; Pledge, 1967; Compagno, 1988; Whitenack and Gottfried, 2010; Cappetta, 1987, 2012). In both histotypes, the outermost layer of the tooth is the enameloid layer (Gillis and Donoghue, 2007). Enax et al. (2012) showed that the mineral in the
8

enameloid layer of the shortfin mako shark, Isurus oxyrinchus, and the tiger shark, Galeocerdo cuvier, previously identified as hydroxyapatite Ca5(PO4)3(OH), is actually fluoroapatite, Ca5(PO4)F. Mammalian enamel is hydroxyapatite, so this difference in mineral composition supports the interpretation that the fluoroapatite enameloid of elasmobranchs differs from true enamel.
Most authors refer to the most exposed tooth in a tooth file as the functional tooth, with all other teeth of the tooth file being replacement teeth. Using only the two terms “functional” and “replacement” overlooks differences in developmental stages and implies that no other teeth in a file function in prey capture or manipulation. Our study offers new observations and definitions for functional, replacement, and developing teeth.
Shark fisheries exist across the world. Because shark teeth preserve well, archaeologists often recover them in sites associated with maritime communities (de Borhegyi, 1961; Kozuch and Fitzgerald, 1989; Rick et al., 2002). Often, single complete or incomplete teeth are recovered. To understand the presence and prevalence of a shark species in a historical fishery, archaeologists compare their find to descriptions of whole teeth and their gross morphology. In other cases, shark teeth are found not as byproducts of a society’s livelihood but as sought-after materials used to make ornaments or weapons with direct cultural significance (Leavesley, 2007; Drew et al., 2013). In these cases, shark teeth offer insight to a community’s use of marine resources and the symbolism those resources take on (Leavesley, 2007). For thorough analysis of such artifacts, it is necessary to identify the teeth to species. Identified teeth may be used to infer the symbolic importance of the artifact. For
9

example, a tooth belonging to a large, predatory species may indicate that a collaborative effort or extensive planning was needed to land such a large and potentially dangerous animal (Leavesley, 2007).
One inspiration for this study was the discovery in 2011 of two partial shark teeth in an archeological excavation on Smuttynose Island, Maine. Smuttynose is one of eight islands in the Isles of Shoals archipelago, spanning New Hampshire and Maine, and archaeological excavations there have been the subject of a fascinating recent account (Robinson, 2012). Based on our documentation of the teeth and dentitions of lamnid sharks endemic to the Gulf of Maine, we were able to identify these two partial teeth to the species level, demonstrating the use of non-destructive computed tomography imaging to identify shark teeth when parts of the tooth are missing.
Studies of great white shark teeth often rely on tooth sets. Our approach is to study intact dentitions insofar as possible, using preserved or dried jaws to understand more about the geometry and development of the dentition as a whole. Our approach led us to discover features of the jaws that help to recognize homologies of tooth loci.
We describe and illustrate the gross morphology, arrangement, and morphometry of the teeth and dentition of Carcharodon carcharias using nondestructive, high-magnification, high-resolution computed tomography (CT) to examine tooth structure, development, and replacement. We use 2-D and 3-D models of functional and developing teeth reconstructed from CT data sets to illustrate anatomy.
10

Materials and Methods De Maddelena and Heim (2009) provide a general reference to specimens of
great white sharks in United States museums. In addition to specimens that they noted, we also studied specimens from the Northeast Fisheries Science Center Narragansett Laboratory, at the Australian Museum, at the Queensland Museum, and photographs of an intact specimen in the Museum of New Zealand Te Papa Tongarewa. Institutional Abbreviations
AMNH, American Museum of Natural History (New York, NY); AMS, Australian Museum (Sydney, Australia); ANSP, Academy of Natural Sciences of Philadelphia (Philadelphia, PA); CUMV, Cornell University Museum of Vertebrates (Ithaca, NY); FLMNH, Florida Museum of Natural History (Gainesville, FL); GHC, Gordon Hubbell Collection (specimens not labeled with field numbers were assigned identification numbers based on the date of acquisition, day/month/year; Gainesville, FL); MCZ, Museum of Comparative Zoology at Harvard University (Cambridge, MA); MNZ, Museum of New Zealand Te Papa Tongarewa (Wellington, NZ); NMFS, National Marine Fisheries Service (Northeast Fisheries Science Center, Narragansett, RI); QM, Queensland Museum (Brisbane, Australia); UF, University of Florida (Gainesville, FL); USM, University of Southern Maine (Portland, ME). Materials Examined
In the following list of specimens, we include total length (TL) or fork length (FL) if known. Based on tooth morphology, we could classify specimens lacking TL or FL data as juvenile (JUV), subadult (SUBAD), or adult (ADULT). Specimens with
11

teeth bearing lateral cusplets are juveniles. In larger specimens with teeth lacking lateral cusplets, we used crown height of the second tooth of the upper jaw (P2) to classify specimens as subadults or adults. Specimens in which P2 was < 22 mm are subadults; those in which P2 ≥ 22 mm are adults. Our system is based on Randall (1973: Fig. 2A; 1987) and Gottfried et al. (1996), who established that crown height closely correlates with TL and Castro (2011) who observed that, although exact age and size at maturity are unknown for Carcharodon carcharias, total length at maturity is likely > 340 cm. Many of the NMFS specimens studied were juveniles, originally noted by Casey and Pratt (1985), who provide data on the smallest free-living specimens.
We studied specimens preserved in alcohol (A) or as dried jaws (DR), individual teeth (IT), or frozen specimens in which soft tissues were intact (F).
Carcharhinus leucas: CUMV 97581 (1 IT, fully formed upper tooth, ADULT); CUMV 90375 (1 DR, SUBAD); CUMV 95352 (1 DR, complete skeleton, JUV); CUMV 95741 (1 DR, complete skeleton, SUBAD).
Carcharodon carcharias: AMNH 53095 (1 DR, SUBAD); AMS I.34192-001 (1DR, SUBAD); AMS-I.44959-001 (1 DR, SUBAD); AMS I.45579-001 (1 DR, SUBAD); ANSP 69984 (1 DR, ADULT); ANSP 50982 (1 DR, JUV); CUMV 97912 (1 IT, fully formed tooth, JUV); FLMNH sop # 020105018.011 (1 DR, 237 cm TL, SUBAD); FLMNH sop # 29905026.023 (1 DR, 227 cm TL, SUBAD); GHC 06011997 (1 DR, 488 cm TL, ADULT); GHC 09101981 (1 DR, 244 cm TL, SUBAD); GHC 21091985 (1 DR, 536 cm TL, ADULT); GHC F111582 (24 IT, complete set of functional teeth excised from the left side of top and bottom jaws, 519
12

cm TL, ADULT); GHC F7687 (24 IT, complete set of functional teeth excised from the left side of top and bottom jaws, 518 cm TL, ADULT); GHC H8993 (24 IT, complete set of functional teeth excised from the left side of top and bottom jaws, 518 cm TL, ADULT); GHC F12484 (1 DR, 412 cm TL, ADULT); GHC 06111985 (1 DR, 563 cm TL, ADULT); GHC 03011994 (1 DR, 474 cm TL, ADULT); GHC 22031984 (1 DR, 594 cm TL, ADULT); GHC 23041992 (1 DR, 379 cm TL, ADULT); MCZ 153575 (1 DR, lower left jaw quadrant, ADULT); MCZ 36470 (1 A, head and pectoral girdle, JUV; this specimen was partially dissected and was the basis for a study by Wilga (2005), CT-scanned in this study); MNZ P.052022 (1 A, 280 cm TL, whole specimen, SUBAD, we studied photographs of this specimen taken during its preparation by MNZ personnel); NMFS 1 (1 DR, 241 cm TL, JUV); NMFS 2 (1 DR, 224 cm TL, JUV); NMFS 3 (1 DR, JUV); NMFS 4 (1 DR, JUV, CT-scanned in this study); NMFS 5 (1 DR, 156 cm TL, JUV, CT-scanned in this study); NMFS 6 (1 DR, JUV); NMFS 7 (1 DR, JUV); NMFS 8 (1 DR, JUV, CT-scanned in this study); NMFS 9 (1 DR, JUV); NMFS 10 (1 DR, JUV); NMFS 11 (1 DR, SUBAD, CTscanned in this study); NMFS 12 (1 DR, SUBAD, CT-scanned in this study); NMFS F1 (1 F, 219 cm TL, SUBAD); NMFS F2 (1 F, 157 cm FL, SUBAD); UF 48285 (1 DR, 262 cm TL, SUBAD); USM 9000 (1 DR, partial tooth identified here as a replacement tooth, CT-scanned in this study); QM I.6973 (1 DR, 4 m est. TL, ADULT).
Isurus oxyrinchus: AMNH 043040SD (1 DR, SUBAD); AMNH 22057SD (1 DR, partial tooth file from left lower jaw); CUMV 97645 (1 DR, jaws sawed to isolate jaw quadrants, JUV, CT-scanned in this study); CUMV 97455 (1 A, head and gills,
13

JUV, CT-scanned in this study); CUMV 90360 (1 DR, SUBAD); CUMV 90361 (1 DR, SUBAD).
Lamna nasus: CUMV 97646 (1 A, complete skeleton, partially damaged rostral cartilage, jaws separated from skeleton, JUV, CT-scanned in this study); USM 71 (1 DR, partial tooth identified here as a replacement tooth, CT-scanned in this study).
Prionace glauca: CUMV 90366 (1 DR, ADULT); CUMV 90971 (1 DR, ADULT); CUMV 95342 (1 DR, ADULT); CUMV 90972 (1 DR, ADULT). Annotated Anatomical Abbreviations
Many synonymous terms are available to describe the dentition and teeth of sharks. Disagreements about tissue identification further complicate the terminology. We developed terminology for our study based primarily on Capetta (1987, 2012) and Compagno (1988) and note modifications and other sources in the following abbreviation list, including citations to authors of specific terms.
AP, articular process of Meckel’s cartilage; BE, broken edge of the crown of a tooth; CH, crown height, the distance in a straight line from the lowest point to the highest point of the tooth crown (Hubbell, 1996); CPT, serrational cusplet, referring to small enameloid covered cusps on either side of the tooth crown in juvenile great white sharks; note that we do not regard these as homologous to the lateral cusplets of Lamna and other Lamniformes; CRN, crown, the large, central portion of the tooth covered with enameloid (Compagno, 1988); CW, crown width, the width of the tooth across the base of the enameloid (Hubbell, 1996); CW:CH, ratio of crown width to crown height; EN, enameloid, (also known as vitrodentine, Zangerl et al., 1993); HY,
14

hyomandibula; LB, lingual boss on root (also called the peg, Compagno, 1988); LC, lateral cusplet; LD, distal length, length of the distal side of a tooth crown; LDB, lower dental bulla, a hollow posterior chamber in Meckel’s cartilage that houses the replacement and developing teeth of m1-m3 (Shimada, 2005); LQJ, lateral quadratomandibular joint, the lateral of two points of articulation between the upper and lower jaws (Motta and Wilga, 1999); LM, mesial length, length of the mesial side of a tooth crown; M, Meckel’s cartilage (= mandibular cartilage); ml, left quadrant of Meckel’s cartilage; MQJ, medial quadratomandibular joint, the medial of two points of articulation between the upper and lower jaws (Motta and Wilga, 1999); mr, right quadrant Meckel’s cartilage; MS, mandibular symphysis; NP, nutritive pore, a foramen, the largest of which is centrally located on the tooth root where blood vessels and nerves enter the tooth (= central canal of Applegate and Espinosa-Arrubarrena, 1996; medial lingual foramen of Compagno, 1988); OD, osteodentine (also called trabecular dentine by Peyer, 1968, and Zangerl et al., 1993, who discouraged use of the term osteodentine on the grounds that it has been used for diverse non-homologous tissues); OP, orbital process of the palatoquadrate; OR, orthodentine (Peyer, 1968; Zangerl et al., 1993); P, palatoquadrate; PC, pulp cavity, the large compartment within an orthodont tooth or a developing osteodont tooth (Peyer, 1968; Compagno, 1988; Zangerl et al., 1993); PL, left quadrant of the palatoquadrate; PLS, placoid scales; PR, right quadrant of the palatoquadrate; PS, palatoquadrate symphysis, the medial symphysis joining left and right halves of the palatoquadrate; QP, quadrate process, a distal crest of the upper jaw that serves as a site of origin for the quadratomandibularis muscle (= palatine process of palatoquadrate of Motta and Wilga, 1999); RNA, root
15

notch angle, which is the angle between root lobes; RT, root, the base of a tooth composed of osteodentine (also referred to as the base, Zangerl et al., 1993), typically hidden by soft tissue in vivo; RTL, root lobe, one of two extensions of a tooth’s root (Compagno, 1988); SR, serrations, series of saw-like notches along the edges of a tooth crown (Applegate and Espinosa-Arrubarrena, 1996); TF, tooth file, a complete sequence of teeth consisting of a functional tooth (or teeth) and all of the developing teeth lingual to it (= tooth row of Compagno, 1988); TL, tooth locus (in the sense of Bemis et al., 2005; this is synonymous with the term tooth position used by Shimada, 2005); TI, tooth inclination, the degree to which the apex of the crown is off center (Shimada, 2005); TN, tooth neck, the region between the base of the enameloid tissue and the osteodentine of the root, most prominent on the lingual side of the tooth (Ebert and Stehman, 2013; also known as the dental band, Applegate and EspinosaArrubarrena, 1996); TW, tooth wells; UDB, upper dental bulla, a hollow posterior chamber in the palatoquadrate that houses the replacement and developing teeth of P1P3 (Shimada, 2005); VC, vascular canal, a channel within osteodentine for blood vessels, also referred to as pulp cavity remnants and vertical vascular tubules by Zangerl et al. (1993). Measurements
We used digital calipers to measure crown width (CW) and crown height (CH) of the first functional tooth of each tooth file in dry jaws or in sets of individual teeth to the nearest 0.1 mm (Fig. 5). When the first functional tooth was damaged, missing, or pathologically abnormal, we scored it as NA. Measurements were in straight lines
16

and did not follow the curvature of the tooth. CW measures the widest part of the crown; CH measures the greatest distance from the base of the crown to its apex.
Tooth inclination refers to the position of a tooth’s apex relative to its crown (Fig. 6). To estimate tooth inclination, we measured the lengths of the mesial (LM) and distal edges (LD). As shown in Figure 6, we used LM/LD to estimate tooth inclination. Tooth inclination < 1.0 means the tooth is mesially inclined; tooth inclination = 1.0 means the tooth is symmetrical; tooth inclination > 1.0 means the tooth is distally inclined.
Except for AMNH 53095, in which we measured every functional tooth, we measured teeth on the upper and lower left quadrants of each jaw. We arbitrarily chose to measure left quadrants because the first 13 specimens examined had more complete teeth in the upper left quadrant than in the upper right quadrant.
We used mixed models incorporating random and fixed effects to understand morphometric differences between tooth types (e.g., upper anterior teeth, intermediate tooth, lateral teeth, and posterior teeth) in subadult and adult specimens using JMP Pro (version 10.0.0; SAS Institute, Cary, North Carolina). Our dependent variable was the ratio of crown width:crown height, here abbreviated as CW:CH. Preliminary study showed that these ratios were not normally distributed, so we log transformed them to better meet assumptions of our mixed model analyses. Initial fixed variables were crown height, maturity (subadult or adult), tooth locus (1 to 11), tooth type (scored 1 to 4 for upper jaw teeth and 1 to 3 for lower jaw teeth to reflect the scheme by Applegate and Espinosa-Arrubarrena (1996) shown in Fig. 2) and tooth number nested
17

within tooth type. Shark ID was a random effect. We removed variables from our mixed model analysis if they had no statistical significance.
We CT scanned AMNH 53096 (SUBAD), NMFS 4 (JUV), NMFS 5 (JUV), NMFS 8 (JUV), NMFS 11 (SUBAD), NMFS 12 (SUBAD), CUMV 97581 (ADULT), and CUMV 97455 (JUV) using an Xradia Versa XRM-500 nano-CT scanner in the Biotechnology Resource Center Multiscale Imaging Facility at Cornell University to generate slice files as stacks of .tiff image files, with as many as 1,200 files per scan. We scanned MCZ 36470 (JUV) in a Toshiba Aquilion 16 LB CT scanner at the Cornell University College of Veterinary Medicine. This instrument saves files as DICOM images. We used CT data sets to make 2-D and 3-D digital reconstructions using Osirix™ (version 4.0 64-bit edition) Digital Imaging and Communication in Medicine (DICOM) imaging software (Rosset et al., 2004) on Apple Macintosh computers running OSX 10.8.5. We used 3-D volume reconstruction in Osirix™ to generate detailed virtual models of specimens in which color gradients represent tissue densities adjusted using standard and customized color look-up tables (CLUT). Dense tissues are represented by lighter shades (typically white or yellow in our reconstructions) and less dense tissues by darker shades (typically red in our reconstructions). We used customized CLUTs as needed to reveal teeth, cartilage or soft tissues. To view internal anatomy, we digitally dissected or sectioned 3-D reconstructions within Osirix™. For example, to visualize teeth of the lower jaw, we digitally removed the upper jaw and modified the CLUT to reveal high-density tissues. Our original digital data sets are available as supplementary files. Digital reconstructions of teeth presented in this study have final resolutions between 26µm
18

and 32µm. We captured images using Grab, a screen-capture utility in Mac OS. Figures of 3-D reconstructions generated from CT datasets were rendered in OsriX™, screen-captured as .jpg or .tiff files, and edited in Adobe Photoshop CS5. Photographs and Illustrations
We used a Canon 5D Mark II digital camera to record color macrophotographs and an Olympus DP70 digital camera and software with an Olympus SZX12 stereo microscope to record color microphotographs. We adjusted digital images for color balance and contrast using Adobe Photoshop CS5 and laid out plates, labels and prepared line drawings using Adobe Illustrator CS5. We generated graphs in Adobe Illustrator CS5 using output from Microsoft Excel version 14.1.0 and JMP 10.0.0. Results
Results are organized around Figures 7-31 and in seven subsections Sizes of specimens examined
Figure 7 shows TL and CH of the largest tooth in the jaw of specimens examined in this study (red circles) and CH for specimens lacking TL data (yellow stars) together with data replotted from Randall (1973; black circles). There is a strong positive correlation (r2 = 0.952) between CH (mm) and TL (m) given by the equation:
CH = 9.0215•TL+0.3489 We studied teeth and dentitions of juvenile, subadult, and adult specimens. Specimen NMFS 8 is the smallest individual; it likely measured 1.25-1.5 m TL. The largest specimen examined was an intact jaw from a 5.94 m specimen (GHC 22031984).
19

Our scheme for classifying specimens as juvenile, subadult or adult is indicated beneath the X-axis. Five new specimens of known TL between 2.1 m to 3.5 m are subadults and ten new specimens ≥ 3.5 m are adults (red circles, Fig. 7). Five of the new specimens studied with CT are juveniles; the four others are subadults (yellow stars, Fig. 7). We CT scanned jaws of juveniles and subadults because of space limitations within the high-resolution CT scanners. We also scanned individual teeth of two subadult specimens (NMFS F1 and NMFS F2). General description of jaws and dentition
A 3-D digital reconstruction of MCZ 36470 shows the position of the palatoquadrate and Meckel’s cartilages in relation to the braincase and its rostral cartilage (Fig. 8). Labial cartilages are absent in Lamnidae. The distal region of the palatoquadrate forms the quadrate process (QP, Fig. 8), which articulates with the articular process of Meckel’s cartilage (AP, Fig. 8). The orbital process is present on either side of the palatoquadrate symphysis (OP, Fig. 8). The hyomandibula and ceratohyal are apparent at the distal corner of the jaw joint (HY, CH Fig. 8). We also studied the hyomandibula in ANSP 50982, a dry specimen in which the jaws remain attached to the chondrocranium and elements of the hyoid arch. The open gape of ANSP 50982 preserves the jaws as if they were in the initial phases of a predatory event prior to jaw protrusion, during which the jaws move ventrally forward from the chondrocranium. We studied the intact dorsal and ventral quadratomandibularis muscles in two frozen specimens, NMFS F1 and NMFS F2. Because they were intact, they helped to maintain the natural dimensions and shapes of the jaws. Figure 9 shows the left and right sides of MCZ 36470. Note the interdigitation of the upper and lower
20

teeth (Fig. 9A). Gum tissues and the dental ligament are still intact on the dissected right side of MZC 36470 (Figs. 8B, 9B). A photograph of MNZ P.052022 (Fig. 10) shows the gum tissues and dental ligament anchoring the teeth in the jaw.
Figure 11 shows the intact dried jaws of AMNH 53095 to outline key anatomical features and our system for designating teeth. The upper and lower jaws consist of left and right halves, resulting in four quadrants. The left and right palatoquadrates connect at the palatoquadrate symphysis (PS, Fig. 11). The mandibular symphysis joins Meckel’s cartilages (MS, Fig. 11). The wide jaw joint consists of medial and lateral articular surfaces (MQJ, LQJ, Fig. 11). In AMNH 53095 a thin layer of connective tissues was left in place to dry over the joints to maintain connection between upper and lower jaws.
AMNH 53095 has 11 tooth loci in both halves of the upper jaw (Fig. 11). There are also 11 tooth loci in each half of the lower jaw (Fig. 11). We numbered tooth loci 1 through 11 beginning at the palatoquadrate symphysis or the Meckelian symphysis and continuing distally. Tooth loci of the upper jaw are designated with a P (for the palatoquadrate cartilage), which can be followed by L or R to designate left or right quadrant. For example, the third tooth to the left of the palatoquadrate symphysis is PL3. Tooth loci of the lower jaw are similarly numbered, using m (for Meckel’s cartilage), which can be followed by l or r to designate left or right quadrants (Fig. 11).
Heterodonty based on different proportions of the teeth is evident along the length of both the upper and lower jaws (Fig. 11). P1 and P2 have the largest crown heights of any teeth in the jaw. P3 is noticeably smaller than P1 and P2. Teeth decrease in size from locus P4 to P7 but still function in prey capture or manipulation
21

and are as large or larger than the P3 tooth. Teeth in positions P8-P11 are smaller still, and probably play limited roles in prey processing. Teeth in the m1 and m2 positions have the largest crown height in the lower jaw. The m3 tooth is smaller than the first two tooth loci of the jaw. Teeth decrease in size uniformly from the m3 tooth to the distal-most tooth (Fig. 11).
A tooth file consists of the functional, fully developed tooth at the labialmost position in the file and teeth in stages of development lingual to it. We developed an annotation system to specify the individual teeth of a tooth file. For example, in Figure 10, ml1f1 means “left Meckelian tooth file 1, functional tooth 1” and mr1f3 means “right Meckelian tooth file 1, functional tooth 3.” We consider that a tooth files contains three types of teeth: functional, replacement, and developing. We explain more about this terminology and address other details of our annotation system in the section Tooth Development, Replacement, and Histology.
In specimens with intact soft tissues, such as MCZ 36470 (Fig. 9), each tooth file of the palatoquadrate has one prominent functional tooth. This is also the case for palatoquadrate of AMNH 53095 (Fig. 11). Most tooth files of the lower jaw of MCZ 36470 have two functional teeth. For example, there are two fully erupted teeth in tooth file ml1 (Fig. 9) and one partially erupted tooth (not visible in Fig. 9 but confirmed with CT). In MNZ P.052022 (Fig. 10), three functional teeth are present at locus ml1 (mr1f1, mr1f2, and mr1f3) and two functional teeth are present at more distal loci (e.g., mr2f1 and mr2f2). In the intact jaw shown in Figure 11, there are two functional teeth and one newly erupted tooth at mr1 and two functional teeth at ml1 (boxed inset in Fig. 11).
22

The upper dental bulla, a prominent cavity on the lingual side of the upper jaw, houses developing and replacement teeth for tooth files P1 to P3 (UDB, Figs. 8, 12). The lower dental bulla houses tooth files m1 to m3 (LDB Figs. 8, 12). Tooth files P4 to P11 and m4 to m11 are contained individually in cavities known as tooth wells (TW, Fig. 11). On thoroughly prepared skeletal material, such as AMNH 53095, NMFS 12, FLMNH sop # 020105018.011, and jaws in the Gordon Hubbell collection (GHC), tooth wells are evident by ridges on the lingual surfaces of the jaws between the tooth files (Fig. 12). Numerical analyses of teeth and dentition
Measurements of the functional teeth of AMNH 53095 (the specimen shown in Figure 11) further describe the arrangement of teeth in the jaw (Fig. 13). This is an individual specimen, and values for homologous loci in the right and left upper and lower quadrants were simply averaged to generate the figure. Pink bars in Figure 13 highlight P3 and m3, which have been interpreted by previous workers as intermediate teeth. Plots of crown width and crown height show patterns of tooth dimensions in relation to tooth locus (Fig. 13 A and B). P3 is narrower and shorter than P1 and P2 (Fig. 13A). Similarly, m3 is narrower and shorter than m1 and m2 (Fig. 13B).
In the upper jaw of AMNH 53095, CW:CH of P3 is > CW:CH of P1 and P2 (Fig. 13C). CW:CH is approximately the same for loci P4-P7, and increases for P8P11. In the lower jaw, CW:CH of m3 is only slightly greater than the CW:CH of m1 and m2 (Fig. 13D). CW:CH is approximately the same for loci m4-m6, and increases for loci m7-11 (Fig. 13D). These findings may be generalized: teeth closest to the palatoquadrate or mandibular symphyses are relatively taller than more posterior teeth.
23

Figure 13E and F shows tooth inclinations for AMNH 53095, measured as the quotient of the mesial over distal crown lengths (Fig. 6) and averaged for the right and left quadrants. P1 and P2 are nearly symmetrical with a tooth inclination near 1.0 (Figs. 13E). P3 has a mesial inclination (Figs. 11, 13E). Most teeth distal to P4 are distally inclined (Figs. 13E). In the lower jaw, m1 is nearly symmetrical with a tooth inclination near 1.0 (Figs. 13F); m2 is slightly distally inclined, but in this specimen the inclination of m2 appears more prominent because it is next to the mesially inclined m3. Meckelian teeth m4-7 are either symmetrical or slightly distally inclined (Fig. 13F). More pronounced distal inclination of Meckelian teeth occurs from m8-11 (Fig. 13F).
Figure 14 shows CW:CH for each tooth locus for all 20 subadult and adult specimens studied. In the upper jaw, variance of relative tooth dimensions is greatest in P4 and P9 teeth (Fig. 14A). In the lower jaw, variance of CW:CH is greatest from m7 through m11 (Fig. 14B). The general patterns of CW:CH as seen in AMNH 53095 (Figs. 13C,D) typify the entire sample (Fig. 14A,B).
We used a standard least squares mixed model analysis with random and fixed effects in JMP Pro 10.0.0.to analyze CW:CH of palatoquadrate teeth in our sample of subadult (N = 7) and adult (N = 13) specimens. Because CW:CH is a ratio and not normally distributed, we log transformed CW:CH to better meet assumptions of our standard least squares mixed model. Our response variable thus was log CW:CH. Specimen number was a random effect in the model. We included the following fixed effects in our initial model: tooth height, tooth type (according to Applegate, 1965; anterior, intermediate, lateral, or posterior), maturity (subadult or adult), tooth number
24

(loci 1-11 based on position from the symphysis) nested within tooth type, and tooth type crossed with maturity. We successively removed fixed effects that were not significant in predicting log CW:CH. Fixed variables included in the final model were tooth height, tooth type, maturity, and tooth type crossed with maturity. The r2 value for the regression is 0.85. Tooth type and tooth crown height are significant predictors of CW:CH (p < 0.001). Maturity (p < 0.01) and tooth type x maturity (p < 0.0084) also are significant. Variance component estimates assess sources of variation within the data, and 60.5% of the total variance is attributable to individual variation between specimens.
A least squares means differences student’s t-test was used to determine differences in teeth along the jaw. The relative dimensions of P1 and P2 teeth of subadults were statistically different from all other teeth of subadult and adult specimens. Among subadults, no significant difference was found between P3 and P47. P3 teeth of subadults and P1 and P2 teeth of adults lack a significant difference in relative dimensions. Relative dimensions of P8-11 of both subadults and adults are not significantly different from P4-7. P3 teeth of adults are not significantly different from any other teeth in the jaw. Lack of statistically significant differences in tooth dimensions is made apparent in a box and whisker plot (Fig. 14A). Tooth types of Meckel’s cartilage also lack significant differences (Fig. 14B). Beyond tooth file m7, variance in tooth dimensions increases in subadult and adults.
We removed the effect of maturity from the model, combining data from subadult and adults so that the data set represented all specimens lacking juvenile tooth morphologies. Least squares means differences student’s t-test shows that P3
25

differs from P1 and P2 as well as P8-11, but that it is not statistically different from teeth P5-7.
Three groups of teeth are statistically distinguishable in Meckel’s cartilage. Results of a least squares means differences student’s t-test indicate that teeth in the m1, m2, and m3 positions differ with respect to geometry of the crown from all other teeth of the lower jaw. Dimensions of tooth crowns of teeth in positions m4-7 are also distinct and significantly different from other lower jaw teeth. The third group of teeth is m8-11, which differ compared to the other two groups. When the effect of maturity is added to analysis of Meckelian teeth, the only teeth are completely unique in crown dimensions are the m8-11 teeth of adults. Crown dimensions of teeth in positions m13 are not statistically different between subadults and adults. In adult great white sharks, the m1-3 crown dimensions are not statistically different from the dimensions of teeth in the m4-7 positions of subadults. Crown dimensions of m4-7 of adults are not statistically different from m8-11 of subadults.
When models were adjusted to reflect only three tooth types in the lower jaw (anterior, lateral, and posterior) without the effect of maturity, a significant difference was apparent between all types of teeth. No statistical analyses based on crown dimensions support the identification of an intermediate tooth in the lower jaw. Descriptions of teeth
Fully developed teeth consist of crowns and roots (CRN, RT, Fig. 15). Tooth crowns of juvenile great white sharks such as CUMV 97912 are narrow with fine serrations and the characteristic lateral cusplet (CPT, Fig. 15). Teeth of the smallest specimens with intact jaws, NMFS 4 and NMFS 8, lack serrations or only have them
26

in the lower half of the tooth crown. In these juveniles, lateral cusplets are visible in all intact Meckelian teeth, although in the broader teeth towards the distal ends of the jaws the lateral cusplets may be difficult to distinguish from large serrations. Lateral cusplets of m1-4 are frequently pronounced, although not as broad as the lateral cusplets of more distal teeth. Exposed lateral cusplets may be lost to wear, so to determine the presence or absence of lateral cusplets, it is often helpful to examine the tooth lingual to the first functional tooth of a file, which usually has intact undamaged lateral cusplets. Comparison of juvenile specimens shows that m1 teeth are typically the last teeth to lose lateral cusplets during the ontogenetic change in tooth morphology. Other Meckelian teeth may lack lateral cusplets in large juveniles, but m1 teeth retain lateral cusplets.
Figure 16 shows the intact jaw of a subadult (NMFS 12). Teeth of subadult and adult great white sharks lack lateral cusplets but have prominent serrations (SR, Figs. 17 and 18). Roots of fully developed teeth have two lobes (RTL, Figs. 17, 18) composed of osteodentine, which histologically and in surface view resembles bone because roots lack an enameloid surface layer. Root width ≥ crown width in all teeth, and is relatively much wider in more distal teeth. The angle formed between root lobes is the root notch (RNA, Figs. 17, 18). The root notch angle of upper teeth is shallow, whereas the root notch angle of Meckelian teeth is usually much less than 180° (Fig. 18 A, C). There is also variation along the length of the jaw. For example, Figure 18 shows that ml1 has a much more prominent root notch angle than do teeth ml8-ml11.
In well-prepared teeth, individual nutritive pores are visible on the lingual surface of roots (NP, Figs. 17, 18). These nutritive pores are access points for nerves
27

and blood vessels and lead into internal vascular canals of the tooth. Smaller pores surround the large nutritive pore in the center of the root (Figs. 17B, D, 18B, D). In older, drier, or less well-prepared specimens, the large central pore may be the only one visible. If soft tissues cover the root, nutritive pores generally are not visible. Immediately prior to loss of a functional tooth (as in mr1, boxed in Fig. 16), the labial surface of the root may be exposed, but the nutritive pores remain obscured on the lingual side of the tooth. Magnification is needed to see the many small nutritive pores scattered on the labial surface of the root.
Crowns of both upper and lower teeth have flat labial surfaces and convex lingual surfaces. The same is true for the roots, which display the greatest linguo-labial depth on the lingual side beneath the center of the crown. The crowns of lower jaw teeth often hook labially (Fig. 19). This is most evident in juvenile specimens in which the crowns are narrow and the contours of the tooth most prominent. Tooth Development, Replacement, and Histology
P1 and m1 tooth files curve to conform to the shapes of the dental bullae, with the result that replacement and developing teeth do not lie directly lingual to the functional teeth (Fig. 20). Replacement and developing teeth in all other tooth files are approximately aligned to each other.
The PR1 tooth file shown in Figure 21A consists of five teeth (PR1F1, PR1R1, PR1R2, PR1D1 and PR1D2). There is only one functional tooth (PR1F1, Fig. 21A). In P1 or P2 tooth files, the functional tooth is essentially perpendicular to the replacement tooth behind it (PR1F1 and PR1R1, Fig. 21A) and PR1R1 is nearly
28

perpendicular to the jaw. PR2D2 lies almost in contact with the palatoquadrate cartilage.
The mr1 tooth file shown in Figure 21B consists of eight teeth (mr1f1, mr1f2, mr1r1, mr1r2, mr1d1, mr1d2, mr1d3 and mr1d4). There are two functional teeth, mr1f1 and mr1f2 (Fig. 21B). This contrasts with the single functional tooth in the upper jaw (PR1F1). The angle between the functional tooth and the replacement tooth lingual to it is more acute in the lower jaw than it is in the upper jaw (Fig. 21). When the enameloid crown has been backfilled with osteodentine, the root is the final structure to form. The mr1r2 tooth is the first tooth in the file in which the osteodentine structure of the root is visible. Crown development occurs in developing teeth mr1d1 through mr1d4 (Fig. 21B).
The labialmost functional teeth differ from replacement teeth in that nervous and vascular connections are only maintained on the lingual side of the functional tooth. Nutritive pores demarcate these connections (NP, Figs. 22-24). Sagittal sections of 2-D tooth models generated from CT scanned jaws show that nutritive pores are maintained on both the lingual and labial sides of replacement teeth in the upper and lower jaws (Fig. 22). In sequenced sagittal sections of a lower jaw tooth file, nutritive pores leading to vascular canals within the tooth are visible (Figs. 23 and 24).
The basic pattern of differences in tooth files between the upper and lower jaw observed for PR1 and mr1 (Figs. 21-23) extends to more distal loci. Based on CT scanning and study of dry intact jaws, tooth files P1-P7 have between five and six teeth consisting of one functional tooth, two replacement teeth, and two or three
29

developing teeth. Tooth files of the lower jaw typically have two or three functional teeth, three replacement teeth, and three or four developing teeth.
We examined tooth files of the shortfin mako shark, Isurus oxyrinchus using specimens CUMV 97455, CUMV 90360, and CUMV 90361 (Fig. 25). The number of teeth within a tooth file differs with tooth position, jaw, and species among lamnids. The point at which a replacement tooth erupts from the soft tissue cannot be used as the sole indicator of functionality. The first replacement tooth in great white sharks may or may not be erupted (Fig. 25B). Additionally, a fully formed tooth in CUMV 97455 mr1 tooth file was not erupted but was heavily mineralized and fully formed (Figs. 25, 26).
In developing teeth, the enameloid apex of the tooth crown is the highestdensity structure that is visible (EN, Fig. 22). The enameloid crown is fully developed by the time the tooth is the fourth or fifth lingual tooth from the functional tooth. By the time a great white shark tooth is fully formed, osteodentine within the pulp cavity and root has mineralized. The mineralization is visualized using 2-D reconstructions of CT data as the osteodentine within the crowns becomes increasingly dense. (OD, Figs. 23, 24).
Fully formed teeth of the great white shark have a pulp cavity filled with osteodentine. Covering the filled pulp cavity is a thin layer of orthodentine under the enameloid crown. This condition is referred to as the osteodont histotype (Fig. 27A). This differs from the condition in many other elasmobranchs, which have an orthodont histotype with a prominent pulp cavity, as exemplified by the bull shark, Carcharhinus leucas (PC, Fig. 27B). By virtually sectioning the crowns of an
30

osteodont great white shark tooth and an orthodont bull shark tooth using CTgenerated digital models, the layers of tissue are apparent. The pulp cavity of the orthodont bull shark tooth is contrastable with the osteodentine-filled crown of the great white shark. The layer of orthodentine in the great white shark tooth is relatively thin compared to the layer of orthodentine in the orthodont bull shark tooth (Fig. 27C, D).
Figure 28 shows the enameloid crown and osteodentine core of a broken developing tooth (ml1d2) from MCZ 153575. Removed from its crown, the pattern of trabeculae in the osteodentine is apparent. The osteodentine conforms closely to the shape of the crown but does not enter its serrations. Osteodentine does not fill the entire crown nor does it connect to a root structure.
The process by which the pulp cavity fills with mineralized osteodentine is sudden, occurring in the replacement teeth and marked by increased tissue density. Deposition of the osteodentine matrix that fills the crown is observable over the course of tooth development, beginning in the second developing tooth (Fig. 29). In teeth of the upper jaw, the process is hastened, and changes appear more sudden due to there being fewer teeth per tooth file in palatoquadrate files than Meckelian files. Osteodont teeth have a much thinner layer of orthodentine between the pulp cavity and the enameloid crown. Mineralization of the root continues in replacement teeth. CT scans show the mineralization process. Figure 29 represents tissue density using a color gradient. In older teeth, the denser, heavily mineralized osteodentine is lighter in color. Less dense, newly formed osteodentine is dark red, indicating less mineralized tissue. Of the dentine tissue present in a tooth, the osteodentine of the root is the densest. The
31

densest tissue, the enameloid, is colored white or off-white in CT-generated models (Fig. 29).
It is difficult to accurately count the number of teeth in a tooth file of a dried specimen because such specimens often lack the hollow enameloid crowns that formed at the end of the dental lamina. These hollow crowns lack any direct ligamentous attachment to the jaw and so are easily lost if all of the soft tissues holding the tooth in place and filling the pulp cavity are cleaned away. In specimens with intact soft tissue, developing teeth are not visible without dissection, histological preparation, or the use of imaging technologies such as x-rays, CT scanning, or MRI.
The youngest developing teeth in a tooth file lack roots (Figs. 21, 22, 29). Older developing teeth in a file have partially developed roots (Figs. 21, 22, 29). In still older replacement teeth, a framework of osteodentine forms the structure of the root and fills the pulp cavity, giving the tooth its osteodont histotype. Such replacement teeth are not yet in a functional position, but all mineralized parts of the tooth are present. Functional teeth are fully formed, erupted from the gum tissue, and have mineralized roots. This scheme allows identification of specific teeth in a tooth file in a manner similar to the identification of specific tooth files within the jaw. Developing teeth are labeled D1 to Dn, where n is the number of developing teeth (Figs. 21, 22, 29). Replacement teeth are indicated in the same way, using R1 to Rn, where n is the number of replacement teeth. Functional teeth are F1 through Fn where n is the number of functional teeth.
In summary, we characterize the three stages in tooth formation as follows: 1. Developing teeth
32

2. Replacement teeth 3. Functional teeth Lateral Cusplets, Serrational Cusplets, and Variations in Lamnids The teeth of Lamna have prominent lateral cusplets (LC, Fig. 30A). In contrast, the teeth of juvenile great white sharks bear structures that we term serrational cusplets (CPT, Fig. 30 B, C). We distinguish these two structures because they develop differently. Note in Figure 30A that the lateral cusplets of Lamna nasus are visible in the very earliest stages of tooth development and that they develop independently from the central crown of the tooth. These lateral cusplets are not initially attached to the tooth crown and only held next to it by soft tissues. Only later in development do dentine and enameloid connect the lateral cusplets to the tooth crown of Lamna. Note in Figure 30 B, C that the serrational cusplets of Carcharodon carcharias form at the base of the enameloid crown only when it reaches its final stages of structural development. Figure 31 compares key structural features of the three extant genera of Lamnidae. Among extant lamnids, Lamna has lateral cusplets, Isurus lacks any structures in these positions, and Carcharodon has serrational cusplets. Only Carcharodon is known to have serrations. Carcharodon has the broadest and most linguo-labially flattened teeth. Meckelian tooth files of Lamna and Carcharodon typically have one or two functional teeth whereas Isurus can have three or more. The labial-most functional tooth in Isurus is closer to the next tooth in its tooth file relative to Lamna and Carcharodon. Not shown in Figure 31 but visible in several other figures such as Figure 21A, the palatoquadrate tooth files of C. carcharias present the
33

largest distance between the labial-most functional tooth and the first replacement tooth. Identification of teeth from an archaeological dig at Smuttynose Island
Two partial shark teeth and a single shark vertebra were unearthed in 2011 as part of an archeological excavation on Smuttynose Island, the Isles of Shoals, Maine, USA. USM 9000 and USM 71 were found in two different excavation sites near fish cleaning and preparation areas used in the 17th and 18th centuries at the southwest corner of the island. Because root tissue is absent in these specimens, only partial tooth crowns were recovered. As a result, species-specific tooth shapes were incomplete. The vertebra is from a lamniform, but we have not been able to determine what species.
In 2011, we provided a preliminary identification of the larger tooth as from Carcharodon carcharias. Here, we confirm this and extend our observations about where this tooth came from in the jaw. The size of the partial crown and serrations on USM 9000 indicate that the tooth came from a large, macrophagous shark (Fig. 32). Large predatory shark species common to the Gulf of Maine that have prominently serrated teeth include Carcharhinus obscurus, Carcharhinus longimanus, Prionace glauca, and Carcharodon carcharias. Carcharhinus obscurus, Carcharhinus longimanus, and P. glauca teeth are carcharhinid sharks that have an orthodont histotype. CT scanning and digital sectioning of USM 9000 reveals that it has an osteodont histotype (Fig. 32D). The histotype, size, and serrations allow USM 9000 confirm its identification as the tooth of a great white shark. Based on its estimated CW:CH, we interpret that it is an upper jaw tooth, perhaps from the PL5 to PL8 tooth
34

files based on the degree of inclination. The partial mineralization of osteodentine within the crown indicates that USM 9000 is likely a replacement tooth. This may also explain why the tooth is incomplete because its root is not yet developed.
USM 71 has no serrations and lacks pronounced inclination and uniform tapering (Fig. 33A, B, and C). Such inclination and tapering are typical of extant mako sharks, Isurus oxyrinchus and I. paucus and the absence of these traits in USM# suggests that the tooth did not originate from a member of the Isurus genus. CT scanning and digital sectioning of USM 71 reveals an osteodont histotype (Fig. 33D), ruling out the possibility that it is a lower jaw tooth of a carcharhinid. USM 71 exhibits the same crown morphology and osteodont histotype of Lamna nasus specimen CUMV 97646. The tooth is worn, and no root is present. USM 71 lacks the lateral cusplets found in intact functional teeth of L. nasus. The absence of cusps in USM 71 is probably due to postmortem wear. A thick layer of enameloid extends to the broken base of the crown, supporting our interpretation that the lateral cusplets were lost due to wear. Discussion
There is no reason why these names may not be modified and new terms added if there is a real need for them. In time the terminology of tooth types should become stable and will with common usage give us a valuable tool in work with both recent and fossil sharks.
- Shelton P. Applegate (1965: 6)
35

Tooth Characters and Phylogenetic Interpretations of Lamnidae Because serrational cusplets of the teeth of Carcharodon carcharias form as
crown development reaches completion, and the serrational cusplets are connected to and continuous with the tooth’s serrated edges, we interpret that the serrational cusplets of C. carcharias are modified serrations and not true lateral cusplets such as those of Lamna nasus. In contrast to these serrational cusplets of Carcharodon, true lateral cusplets in Lamna form independently as miniature crowns that subsequently connect to the larger central crown after the osteodentine of the tooth begins to form. This developmental difference between serrational cusplets of C. carcharias and true lateral cusplets of L. nasus has implications for interpreting phylogenies of Lamnidae based on tooth characters. Until now, phylogenetic studies of Lamnidae have assumed that the serrational cusplets of Carcharodon are homologs of true lateral cusplets of Lamna. Based on our preliminary survey, true lateral cusplets appear also to occur in the other macrophagous Lamniformes including Mitsukurina, Carcharias and Odontaspis.
Long and Waggoner (1996: table II and fig. 4B) prepared and analyzed a data matrix of 20 dental characters for the eight extant macrophagous genera of lamniforms. They recovered a phylogeny in which Carcharodon and Lamna are sister taxa and Isurus is the outgroup. At the time, this was a heterodox interpretation that contrasted with a phylogeny based on morphological and reproductive characters (Compagno, 1990). It also conflicted with the first molecular phylogenetic study of Lamniformes, published in the following year by Naylor et al. (1997). Long and
36

Waggoner’s (1996) heterodox interpretation has been repeatedly cited and their tree republished as recently as 2012 (Capetta, 2012: fig. 174).
We identified many problems with Long and Waggoner’s (1996) study, ranging from inconsistencies in the numbering of characters in the data matrix (shown in their table II and fig. 4B) to character definitions that are difficult to interpret or apply because there are no illustrations of the different character states. Nor do they explain their system for recognizing tooth homologies. Setting aside these problems for the moment, their interpretation that Carcharodon and Lamna are sister taxa is supported by only one character in their recoded data matrix (Long and Waggoner, 1996: table II): Character 10, distal inclination of lateral teeth. This is a poorly explained character that is not illustrated. Furthermore, lateral tooth inclination differs between the two extant species of Lamna. Lamna ditropis has more distal inclination of the lateral teeth than does Lamna nasus (Fig. 3). Thus, we would rescore Lamna as a 2, not a 1 in their matrix (Long and Waggoner, 1996: table II), which removes all support for Long and Waggoner’s (1996) heterodox conclusion about the relationships of Lamna, Carcharodon and Isurus. With this rescored character, the phylogenetic relationships of Lamna, Carcharodon and Isurus are as shown in Figure 1. This phylogeny for extant Lamnidae agrees with molecular-based phylogenies proposed by Naylor et al. (1997; 2012), Martin et al. (2002), and Vélez-Zuazo and Agnarsson (2011), as well as morphology-based phylogenies of Compagno (1990) and Achebe et al. (2013). We are preparing a further and more detailed critique of the many problems with the characters and matrices provided by Long and Waggoner (1996).
37

The other major paper to consider dental characters and lamniform phylogeny is Shimada (2005: fig. 6), who analyzed three matrices to explore the potential of dental characters to resolve lamniform phylogenies. One matrix is based on dental and non-dental characters combined (48 characters), one is based on non-dental characters (29 characters) and the third is based on dental characters alone (19 characters). In contrast to Long and Waggoner (1996), who did not distinguish between the species of Isurus and Lamna, Shimada (2005) studied all five extant species of Lamnidae. Shimada (2005) redefined and rescored some of the dental characters defined by Long and Waggoner (1996). For example, both studies include “Tooth striations” (Long and Waggoner 1996: Character 6) or “Long, fine vertical grooves on lingual surface of central cusp” (Shimada, 2005: Character 47). In Long and Waggoner (1996), Character 14 is “Symphysial teeth” whereas Shimada (2005) broke this down into Characters 43 and 44, for the presence of upper and lower symphysial teeth respectively, although he did not find any taxa that had a difference in symphysial teeth in the upper versus the lower jaw. One criticism of Shimada’s (2005) data matrix is its incompleteness: many taxa are not scored for dental characters that should be visible if enough specimens are studied. For example, Shimada (2005: Character 48) scored distal lateral cusplets as “?” for both extant species of Isurus, but we have never seen any evidence of such structures in any of the Isurus we examined, nor are they illustrated in any study that we know about. Given the importance of cusplets in interpreting fossil and living lamnids, this scoring is puzzling. Based on the TL data he provided, Shimada (2005) studied subadults and adults specimens of Carcharodon, Lamna, and Isurus. Inclusion of juvenile and adult great white sharks in a single data
38

set may not appropriate based on our findings that maturity can impact tooth morphology. Moreover, more than half of the dental characters Shimada (2005) included in the analyses (characters 43 to 61) are continuous, morphometrically-based characters. For example: Character 51. Distal inclination of central cusp of first upper anterior tooth (A1; Appendix 4): [0] vertical or weakly inclined (mean value <1.10), [1] strongly inclined (mean value > 1.10).
Such continuous characters can be much more difficult to score reliably than presence-absence characters used in other parts of the data matrix. For example, 23 of the 29 morphological characters studied by Shimada are either two or three state characters that can be scored unequivocally.
Each of the three analyses presented by Shimada (2005: fig. 6) differed with respect to the position of Carcharodon. For example, based on dental characters alone, Shimada (2005: fig. 6.3) found that Carcharodon, Isurus, Pseudocarcharias, and Alopias form a clade. In the trees based on morphology + dental characters or on morphology alone, Shimada recovered Lamnidae as monophyletic, although the positions of Carcharodon, Isurus and Lamna differed between analyses. Shimada (2005: 63) stated that discrepancies between trees based on dental and trees based on non-dental characters indicate that dental characters generate “considerable phylogenetic noise.” We cannot agree with this statement because properly defined and scored dental characters have yet to be investigated across all living and fossil Lamniformes. In contrast, until there is definitive evidence otherwise, we suspect that dental characters will prove to be useful tools to investigate lamniform
39

interrelationships and indispensable when investigations expand to include extinct species, most of which are only known from teeth.
The overall similarity of dental-based phylogenies and non-dental phylogenies at the family level indicates phylogenetic signature of dental characters in extant lamnids and dental characters generate useful phylogenetic signals when properly defined. Therefore, better understanding of tooth growth and development and intact dentitions is essential. Although there are only five extant lamnid species, and the evolutionary origins of Carcharodon are still debated, Isurus and Lamna are well represented in the fossil record. A thorough lamnid phylogeny based on dental characters should include extinct taxa. Without the inclusion of these extinct taxa, the misidentification of characters as synapomorphic becomes more likely. For example, current tooth-based phylogenies including Isurus score members of the genus as lacking serrations and possessing a distal blade-like cutting edge (Long and Waggoner, 1996; Shimada, 2005). The implication is that all members of the genus lack serrations as do the extant members. With the inclusion of fossil taxa, such as †Isurus escheri, which has fine serrations on the edges of its tooth crowns (Diedrich, 2013), it is clear that the original character needs revision because it does not reflect all known members of the genus. We note that Capetta (2012: 212) addressed this problem of serrated mako teeth by reassigning †Isurus escheri to “†Carcharodon” escheri. They key to creating useful lamnid phylogenies based on dental characters will be the definition of dental characters correlated to jaw and chondrocranial anatomy or developmental processes. For example, the differentiation of serrational cusplets from true cusplets is based on their appearance during development for more
40

accurate scoring of lateral cusplet presence and serrations. Specifically, based on our new data, we interpret that the clade including Carcharodon and Isurus shares an evolutionary loss of lateral cusplets. After their divergence, serrations evolved. The line leading to extant species of Isurus subsequently lost serrations. In the line leading to Carcharodon, the basal parts of the serrations became specialized juvenile serrational cusplets. Dental Formulae and Variation in Tooth Shape in Lamnidae
Building on Shimada (2002a), we can clarify some aspects of homology recognition needed for effective dental formulae in lamnid sharks. Dental formulae are useful to the extent that they are based on easily recognized homologous features that can be agreed upon by all observers. Shimada (2002a, 2005) compared such homologies in shark dentitions to the well-known patterns of mammal dentitions, noting that in both sharks and mammals the homologies are based on reference points in the jaw, patterns of tooth development, and tooth morphology. For example, a mammal’s canine tooth lies near the anterior margin of the maxilla, and dental bullae in the upper jaws house the P1-P3 tooth files of lamnid sharks. But because lamnids are polyphyodont, ontogenetic changes in tooth morphology occur throughout life. Such ontogenetic changes potentially limit the use of tooth morphology to recognize homologous tooth loci in the jaw.
While it is generally possible to distinguish a large isolated tooth of the upper jaw from a large isolated tooth of the lower jaw based on differences in serrations and the shapes of the crown and root, our results show that is often impossible to unambiguously identify which locus an isolated tooth came from. Thus, based on
41

tooth morphology alone, it is not easy to draw sharp boundaries between types of teeth along the jaw of the sort recognized by Applegate and Espinosa (1996) and shown in Figure 2. Also, we found changes in tooth proportions in relation to maturity. For example, P3 is distinguishable from P1 and P2 in subadults but not in adults. Thus, it is difficult if not impossible to unambiguously identify the locus of an isolated tooth from a specimen of unknown age. These two challenges point to the importance of studying intact jaws rather than isolated tooth sets because characters of the jaws provide additional information essential to identifying homologies of tooth loci.
The most descriptive and unambiguous identification of teeth based on position in the jaw relates to dental bullae and tooth wells, which are present in all specimens of Carcharodon examined, regardless of size. As noted by Shimada (2002a), teeth in positions P1-P3 and m1-m3 are intrabullar teeth because the tooth files for these loci develop within dental bullae. In Shimada’s (2002a) characterization, the remaining teeth distal to P3 or m3 in the upper and lower jaws are extrabullar. A more descriptive term for these teeth might be wellian, because their tooth files develop within tooth wells.
When teeth are considered in the context of their intrabullar or wellian locations, differences in tooth shape become more apparent. Among intrabullar teeth of the upper jaw, P3 has significantly different CW:CH relative to P1 and P2 in subadult and adult great white sharks. Among wellian teeth of the upper jaw, P4-P7 have significantly different CW:CH relative to P8-P11. In the lower jaw, the three intrabullar teeth do not differ in CW:CH, but m4-m7 are significantly different from m8-m11. If teeth are first classified as intrabullar (B or b) or wellian (W or w), second
42

as mesial (M or m) or distal (D or d), and third by the number of teeth in that category,

a tooth formula reliably differentiates tooth types based on testable criteria of tooth

location and geometry. In our scheme, the dental formula for Carcharodon carcharias

is:

BM 1-2 bm 1-3

BD 1

WM 1- 4 WD 1- 3 or 4

wm 1- 4

wd 1- 3 or 4

This dental formula is similar to that of Long and Waggoner (1996) in that it does not

recognize an intermediate tooth in the lower jaw. It differs from interpretations of

Shimada (e.g., 2002a, 2005 and Figure 3 in this paper) who recognized an

intermediate tooth in both the upper and lower jaws.

Several authors have used variations in tooth dimensions and shape to assess

interspecific relationships within Lamnidae (e.g., Long and Waggoner, 1996;

Shimada, 2005; Nyberg et al., 2006). In one specimen we examined (Fig. 34), teeth

were so long and narrow that, but for their serrations, they closely resemble those of

the extinct mako shark †Isurus hastalis (= †Cosmopolitodus hastalis in Cappetta,

2012: p. 215-217 and fig. 201). Additional study of variation in tooth shapes of

Carcharodon is warranted, and it will be especially important to study that variation in

the context of the ontogenetic changes we observed.

Although Shimada (2002a, 2005: character 1) established that the presence of

dental bullae is synapomorphic for Lamniformes, we suggest emending his character 1

to read “Teeth develop in dental bullae or tooth wells.” Left open in prior studies is

why Lamniformes have such dental bullae and tooth wells. Perhaps dental bullae,

which allow the tooth files to form curved series of developing and replacement teeth,

43

are an adaptation for a relatively narrow (in the left-right sense) jaw related to extreme jaw mobility. Tooth Size and Total Length Estimates
Estimation of TL based on tooth crown height in the great white shark is common, but details such as which tooth is measured vary. Techniques for measuring crown height as well as decisions about which tooth is measured differ from author to author. For example, Randall (1973) states that he measured the largest tooth in the mouth. Other workers, such as Santana-Morales et al. (2012) specify that they measured the second anterior tooth in the right side of the jaw (PR2 in this study). These may or may not be the same tooth. The crown height of the second anterior tooth (P2) was the largest tooth in the mouth in approximately half of the specimens we studied. In the other specimens, the first anterior tooth (P1) was larger.
We used three terms to describe the maturational states of specimens we studied: juvenile, subadult, and adult. Our definition of a subadult category is based on two observations. First, it is generally accepted that TL at maturity is > 3.5m (Castro, 2011), and, in males, sexual maturity is also indicated by calcification of the claspers (Pratt, 1996). Second, many specimens that we examined < 3.5 m had already lost the serrational cusplets typical of juvenile great white sharks. For example, there are no serrational cusplets on the teeth of MNZ P.052022 (Fig. 10), so it is not a juvenile. We studied additional photographs of this specimen available from the MNZ. It is a male in which the claspers extend beyond the free rear tip of the pelvic fins. Importantly, these claspers are not yet calcified. Thus, this specimen is not yet sexually mature. Our
44

refined definition of the subadult stage in the ontogeny of great white sharks may be helpful to future life history investigations.
Shimada (2002c) examined the relationship of each functional tooth in the mouth of 12 great white sharks of known TL. He found that any tooth in the mouth could be used to infer TL. Shimada also noted that the P1 tooth, P5 tooth, and P9 tooth of the great white shark each have unique regression lines correlating the CH of each tooth to the TL of the animal. His analysis depends on the recognition of tooth homologies proposed in Shimada (2002a), and to apply his findings to estimate TL, one must know the position of the tooth, which may be difficult if only a single tooth is recovered.
It is difficult to measure the crown width and height in specimens in which soft tissues are intact. When dried jaws and preserved or fresh materials are included in the same dataset, care must be taken to measure the crown width and height at the base of the enameloid crown, not from the point at which the tooth disappears beneath the gum tissue. A large but unknown amount of shrinkage occurs during the drying process, but this presumably relates to the dimensions of ligaments and cartilage and not to the dimensions of fully formed functional teeth. In specimens such as MCZ 36470, a preserved head, measurements are difficult to obtain using calipers because fixation greatly reduces the jaws’ flexibility, and the rest of the specimen prevents the insertion of measuring devices into the oral cavity. Tooth Histotypes
There is a long history of comparisons of two histotypes of elasmobranch teeth, beginning with Agassiz (1833-1843) and Owen (1840-1845). Several authors
45

credit Thomasset (1930a,b) for labeled interpretations comparing these two histotypes, yet the figures in Thomasset’s paper do not actually make such a comparison (Fig. 35A). Bertin (1958) is another widely cited source for histotype comparisons, but he incompletely labeled his figures (Fig. 35B) and incorrectly credited them to Thomasset (1930a). Pledge (1967) redrew and relabeled Bertin’s (1958) illustrations. Cappetta (1987, 2012) also redrew and relabeled Bertin’s figure (Fig. 35C). Whitenack et al. (2010) schematized Bertin’s illustration, omitted one tissue layer, and changed the shape of the pulp cavity (Fig. 35D). In replicating or modifying existing figures, these authors changed terminologies, using pseudodentine, trabecular dentine or osteodentine for the same tissue layer. Peyer (1968: 64) preferred the term trabecular dentine to the term osteodentine, but others, such as Capetta (2012: 25) equate them and use both terms. Zangerl et al. (1993) provided original figures (Fig. 35E) and a terminology most similar to that of Peyer (1968). Compagno (1988: Fig. 3.6) provided original micrographs to illustrate side-by-side histological comparisons of orthodont (Negaprion) versus osteodont (Lamna) teeth. He used the term osteodentine to describe the tissue of the root and infilling of osteodont teeth.
While many authors draw a sharp distinction between orthodont and osteodont teeth, the phylogenetic importance of such differences is unclear. Thomasset (1930a) illustrates variation in orthodont teeth within Carchariniformes, showing that size and shape of the pulp cavity is not consistent within the order. Compagno (1988) reports that the osteodont condition evolved from an ancestral orthodont condition within the genus Hemipristis. Our study documents the osteodont condition in Isurus, Carcharodon and Lamna. Published observations of Whitenack et al. (2010) and our
46

observations of Carcharias taurus and other odontaspids indicate that the osteodont condition is widespread among Lamniformes.
Tooth crowns of teeth exhibiting the osteodont histotype consist of a thick osteodentine-filled core under a thin layer of orthodentine under an enameloid crown. This contrasts with orthodont tooth crowns that have a pulp cavity surrounded by orthodentine and enameloid. Whitenack et al. (2010) report equal hardness of the enameloid tissues of representative osteodont and orthodont teeth from Carcharias taurus and Sphyrna tiburo respectively. They further report that osteodentine is significantly harder than orthodentine. The functional significance of this difference has yet to be tested. Wroe et al. (2008) found that large great white sharks may bite with a force exceeding 18,000 N, so it is conceivable that the osteodont histotype may be suited for such extreme bite forces due to the solid crown construction of hard enameloid tissue and osteodentine. Habegger et al. (2012) found that the bull shark, Carcharhinus leucas, has the largest anterior bite force of any elasmobranch after the effect of mass is removed, 2,128 N. This value was second only to the great white shark. These results are counterintuitive because the bull shark has clearly defined orthodont teeth. The evolution and functional anatomical implications of tooth histotypes in sharks has yet to be studied in detail. Summary and Remarks on Future Studies
Our study of the dentition of Carcharodon carcharias describes not only individual tooth morphology but also gross dental arrangement in juveniles, subadults and adults. Ontogenetic changes in tooth morphology correlated with maturational data indicate a subadult stage in which the key feature of juvenile teeth – the presence
47

of serrational cusplets – is absent, but sexual maturity has not yet been achieved. We emphasize the importance of studying complete dentitions in intact jaws whenever possible and relate our findings to estimates of TL based on tooth size. Our descriptive statistical analyses suggest that previously proposed tooth categories cannot be recognized across all life stages of the great white shark. We propose a modified dental formula for the great white shark based on observable anatomical features. We applied high-resolution nano-CT scanning to the study of great white shark teeth and provide a step-by-step description of tooth formation in C. carcharias. Consequently, we propose a new, more specific method of differentiating teeth in a tooth file and identifying a single tooth’s stage of development. We applied CT techniques to study two teeth found during an archeological excavation on Smuttynose Island. Finally, we critique dental characters used in previous phylogenetic studies of Lamniformes and interpret that the serrational cusplets of Carcharodon are not homologous to the lateral cusplets of Lamna.
Despite progress, variations in tooth morphology within fossil and living species of Carcharodon are incompletely known. For example, we have yet to fully compare teeth and dentitions of different geographic populations (e.g., Western North Atlantic compared to Australia-New Zealand). To place extinct species of Carcharodon within an overall phylogeny of Lamniformes, it will be important to make even more in-depth quantitative studies of dental variation in extant lamniforms and review and revise dental characters used in phylogenetic studies. Presence/absence characters based on tooth development and overall dentition rather than individual tooth morphometrics may prove especially useful.
48

Computed tomography offers benefits for investigating the arrangement and development of elasmobranch teeth. It enables validation and refinement of observations made in previous studies without destructive sectioning of specimens. Many recent paleontological studies have used CT to reconstruct whole or partial vertebrate fossils to visualize elements such as jaw suspension in †Helicoprion or the brain case of the hybodont shark †Tribodus limae (Tapanila et al., 2013; Lane, 2010). Others use CT imaging to evaluate similarities in morphology between extant and extinct species such as the great white shark (Wroe et al., 2008) or to explore morphological distinctions or gather evidence to support the revision of phylogenies (e.g., Longo et al., 2013; Pradel et al., 2013; Rygg et al., 2013; Mollen et al., 2012). As nano-CT becomes more available to researchers, we can expect its application to vertebrate morphology grow.
49

REFERENCES
Achebe, I. B., Shimada, K., Reilly, B., and Rigsby, C. K. 2013. Cranial musculature in extant crocodile shark, Pseudocarcharias kamoharai (Lamniformes: Pseudocarchariidae) and its evolutionary implications. Journal of Fossil Research, 46: 20-28.
Agassiz, L. 1833–1843. Recherche sur les Poissons fossiles, 5 vols. Imprimerie de Petitpierre, Neuchâtel et Soleure.
Applegate, S. P. and Espinosa-Arrubarrena, L. 1996. The fossil history of Carcharodon and its possible ancestor Cretolamna. In Great White Sharks: The Biology of Carcharodon carcharias. A. P. Klimley and D. G. Ainley, Eds., Academic Press, New York. 19-36.
Applegate, S. P. 1965. Tooth terminology in sharks with special reference to the sand shark, Carcharias taurus Rafinesque. Los Angeles County Museum Contributions in Science, 86: 1-18.
Bemis, W. E., Giuliano, A., and McGuire, B. 2005. Structure, attachment, replacement and growth of teeth in bluefish, Pomatomus saltatrix, a teleost with deeply socketed teeth. Zoology, 108: 317-327.
Bertin, L. 1958. Denticules Cutanés et Dentes. In Traité de Zoologie: Anatomie, Systématique, Biologie. Tome XIII, Agnathes et Poissons, Anatomie, Éthologie, Systématique. P. Grassé, Ed., Masson et Cie, Paris. 505-531.
50

Bigelow, H. B. and Schroeder, W. C. 1948. Sharks. In Fishes of the Western North Atlantic, Parr, A. E., and Olsen, Y. H. (eds.). Sears Foundation for Marine Research, Yale University, New Haven. 59-546.
Budker, P. 1971. The Life of Sharks. Columbia University Press, New York. Cappetta, H. 1987. Chondrichthyes II: Mesozoic and Cenozoic Elasmobranchii (Vol.
2). G. Fischer Verlag. Cappetta, H. 2012. Handbook of Paleoichthyology: Chondrichthyes.-Mesozoic and
Cenozoic Elasmobranchii: Teeth (Vol. 3E). Pfeil. Casey, J. G., and Pratt, H. L., Jr. 1985. Distribution of the white shark, Carcharodon
carcharias, in the western North Atlantic. Memoirs Southern California Academy of Sciences 9: 2-14. Castro, J. I. 1983. The Sharks of North American Waters. Texas A&M University Press, College Station. Castro, J. I. 2011. The Sharks of North America. Oxford University Press, New York. Cione, A. L., Cabrera, D. A., and Barla, M. J. 2012. Oldest record of the great white shark (Lamnidae, Carcharodon; Miocene) in the Southern Atlantic. Geobios, 45: 167-172. Compagno, L. V. J. 1970. Systematics of the genus Hemitriakis (Selachii: Carcharhinidae), and related genera. Proceedings of the California Academy of Sciences, Series 4, 38: 63-98. Compagno, L. V. J. 1988. Sharks of the Order Carcharhiniformes. Princeton University Press, Princeton, New Jersey.
51

Compagno, L. V. J. 1990. Relationships of the megamouth shark, Megachasma pelagios (Lamniformes: Megachasmidae), with comments on its feeding habits. NOAA Technical Report, NMFS 90: 357-379.
de Borhegyi, S. F. 1961. Shark teeth, stingray spines, and shark fishing in ancient Mexico and Central America. Southwestern Journal of Anthropology, 273-296.
De Maddelena, A. and Heim, W. 2009. Great White Sharks in United States Museums. McFarland and Company, Jefferson, North Carolina.
Diedrich, C. G. 2013. Evolution of white and megatooth sharks, and evidence for early predation on seals, sirenians, and whales. Natural Science, 5: 1203-1218.
Drew, J., Philipp, C., and Westneat, M. W. 2013. Shark tooth weapons from the 19th century reflect shifting baselines in Central Pacific predator assemblies. PloS one, 8: e59855. 1-7
Ebert, D. A. 2003. Sharks, Rays, and Chimaeras of California. University of California Press.
Ebert, D. A., Fowler, S., and Compagno, L. 2013. Sharks of the World: A Fully Illustrated Guide. Wild Nature Press, Plympton St. Maurice, Plymouth
Ehret, D. J., Hubbell, G., Macfadden, B. J. 2009. Exceptional preservation of the white shark Carcharodon (Lamniformes, Lamnidae) from the early Pliocene of Peru. Journal of Vertebrate Paleontology, 29:1-13
Enax, J., Prymak, O., Raabe, D., and Epple, M. 2012. Structure, composition, and mechanical properties of shark teeth. Journal of Structural Biology, 178: 290299.
52

Frazzetta, T.H. 1988. The mechanics of cutting and the form of shark teeth (Chondrichthyes, Elasmobranchii). Zoomorphology, 108: 93–107
Gillis, J. A. and Donoghue, P. C. J. 2007. The homology and phylogeny of chondrichthyan tooth enameloid. Journal of Morphology, 268: 33-49.
Glickman, L.S. 1967. Subclass Elasmobranchii. In Y.A. Orlov (editor) D.V. Obruchev, (volume editor) Fundamentals of Paleontology, 11: 292-352. Israel Program for Scientific Translations. Jerusalem.
Gottfried, M. D., Compagno, L. J. V., and Bowman, S. C. 1996. Size and skeletal anatomy of the giant “megatooth” shark Carcharodon megalodon. In Great White Sharks: The Biology of Carcharodon carcharias. A. P. Klimley and D. G. Ainley, Eds., Academic Press, New York. 55-66.
Grady, J. E. 1970. Tooth development in sharks. Archives of Oral Biology, 15: 613619.
Habeggera, M. L., Motta, P. J., Huber, D. R., and Dean, M. N. 2012. Feeding biomechanics and theoretical calculations of bite force in bull sharks (Carcharhinus leucas) during ontogeny. Zoology, 115: 354–364.
Hubbell, G. 1996. Using tooth structure to determine the evolutionary history of the white shark. In Great White Sharks: The Biology of Carcharodon carcharias. A. P. Klimley and D. G. Ainley, Eds., Academic Press, New York. 9-18.
Kemp, N. E. 1999. Integumentary system and teeth. In Sharks, Skates, and Rays: The Biology of Elasmobranch Fishes. W. C. Hamlett, Ed., Johns Hopkins University Press, Baltimore, 43-68.
53

Kemp, N. E. and Park, J. H. 1974. Ultrastructure of the enamel layer in developing teeth of the shark Carcharhinus menisorrah. Archives of Oral Biology, 19: 633-643.
Klimley, A. P., Pyle, P., and Anderson, S. D. 1996. The behavior of white sharks and their pinniped prey during predatory attacks. In Great White Sharks: The Biology of Carcharodon carcharias. A. P. Klimley and D. G. Ainley, Eds., Academic Press, New York. 175-191.
Kozuch, L. and Fitzgerald, C. 1989. A guide to identifying shark centra from southeastern archaeological sites. Southeastern Archaeology, 8: 146-157.
Landolt, H. H. 1947. Über den Zahnwechsel bei Selachiern. Revue Suisse de Zoologie, 54: 305-367.
Lane, J. A. 2010. Morphology of the braincase in the Cretaceous hybodont shark Tribodus limae (Chondrichthyes: Elasmobranchii), based on CT scanning. American Museum Novitates, 3681: 1-70.
Leavesley, M. G. 2007. A shark-tooth ornament from Pleistocene Sahul. Antiquity, 81: 308-315.
Leriche, M. 1905. Les poissons tertiaries de la Belgique. II. Les poissons Éocènes de la Belgique. Memoires Musée Royal d’Histoire Naturelle de Belgique, 3:49– 228.
Long, D. J., Hanni, K. D., Pyle, P., Roletto, J., Jones, R. E., and Bandar, R. 1996. White shark predation on four pinniped species in central California waters: geographic and temporal patterns inferred from wounded carcasses. In Great
54

White Sharks: The Biology of Carcharodon carcharias. A. P. Klimley and D. G. Ainley, Eds., Academic Press, New York. 263-274. Long, D. J. and Jones, R. E. 1996. White shark scavenging on cetaceans in the eastern North Pacific Ocean. In Great White Sharks: The Biology of Carcharodon carcharias. A. P. Klimley and D. G. Ainley, Eds., Academic Press, New York. 293- 307. Long, D. J. and Waggoner, B. M. 1996. Evolutionary relationships of the white shark: A phylogeny of lamniform sharks based on dental morphology. In Great White Sharks: The Biology of Carcharodon carcharias. A. P. Klimley and D. G. Ainley, Eds., Academic Press, New York. 37-47. Longo, S., Riccio, M., and McCune, A. R. 2013. Homology of lungs and gas bladders: Insights from arterial vasculature. Journal of Morphology, 274: 687–703. Luer, C. A., Blum, P. C., and Gilbert, P. W. 1990. Rate of tooth replacement in the nurse shark, Ginglymostoma cirratum. Copeia, 1990: 182-191. Martin, A. P., Pardini, A. T., Noble, L. R., and Jones, C. S. 2002. Conservation of a dinucleotide simple sequence repeat locus in sharks. Molecular Phylogenetics and Evolution, 23: 205-213. Mollen, F. H., Wintner, S. P., Iglesias, S. P., Van Sommeran, S. R., and Jagt, J. W. 2012. Comparative morphology of rostral cartilages in extant mackerel sharks (Chondrichthyes, Lamniformes, Lamnidae) using CT scanning. Zootaxa, 3340: 29-43. Mollet, H. F. and Bourdon, J. A. 1998, February. Elasmobranch dentition terminology. http://elasmollet.org/Ref/row.html. Accessed October 2013.
55

Moss, S.A. 1967. Tooth replacement in the lemon shark, Negaprion brevirostris. In Sharks, Skates, and Rays. P. W. Gilbert, R. F. Mathewson, and D. P. Rall, Eds., The Johns Hopkins Press, Baltimore. 319-329.
Moss, S. A. 1972. Tooth replacement and body growth rates in the smooth dogfish, Mustelus canis (Mitchill). Copeia, 1972: 808-811.
Motta, P. J. and Huber, D. R. 2012. Prey capture behavior and feeding mechanics of elasmobranchs. In Biology of Sharks and Their Relatives, 2nd Ed. J. C Carrier, J. A. Musick, and M. R. Heithaus, Eds., CRC Press, Boca Raton, 152-209.
Motta, P. J. and Wilga, C. D. 1999. Anatomy of the feeding apparatus of the nurse shark, Ginglymostoma cirratum. Journal of Morphology, 241: 33–60.
Naylor, G. J. P. and Marcus, L. F. 1994. Identifying isolated shark teeth of the genus Carcharhinus to species: Relevance for tracking phyletic change through the fossil record. American Museum Novitates, 3109: 1-53.
Naylor, G. J. P., Martin, A. P., Mattison, E., and Brown, W. M. 1997. The interrelationships of lamniform sharks: testing phylogenetic hypotheses with sequence data. In: Kocher, T.D. and Stepien, C., Eds., Molecular Systematics of Fishes. Academic Press, New York, 199–218.
Naylor, G. J., Caira, J. N., Jensen, K., Rosana, K. A., Straube, N., and Lakner, C. 2012. Elasmobranch phylogeny: A mitochondrial estimate based on 595 species. In Biology of Sharks and Their Relatives, 2nd Ed. J. C Carrier, J. A. Musick, and M. R. Heithaus, Eds., CRC Press, Boca Raton. 31-56.
56

Nyberg K. G., Ciampaglio C. N., and Wray, G. A. 2006. Tracing the ancestry of the great white shark, Carcharodon carcharias, using morphometric analyses of fossil teeth. Journal of Vertebrate Paleontology, 26:806–814.
Owen, R. 1840 Odontography. 2 Vols. ixxiv + 655 pp., 1-37 pp. + 150 PI. Bailliere, London.
Peyer, B. 1968. Comparative Odontology. University of Chicago Press, Chicago. Pledge, N. S. 1967. Fossil elasmobranch teeth of south Australia and their
stratigraphic distribution. Transactions of the Royal Society of South Australia, 135-164. Pradel, A., Didier, D., Casane, D., Tafforeau, P., and Maisey, J. G. 2013. Holocephalan embryo provides new information on the evolution of the glossopharyngeal nerve, metotic fissure and parachordal plate in gnathostomes. PLoS one, 8: e66988. 1-7 Pratt, H. L., Jr. 1996. Reproduction in the male white shark. In Great White Sharks: The Biology of Carcharodon carcharias. A. P. Klimley and D. G. Ainley, Eds., Academic Press, New York. 131-138. Purdy, R. W. and Francis, M. P. 2007. Ontogenetic development of teeth in Lamna nasus (Bonnaterre, 1758) (Chondrichthyes: Lamnidae) and its implications for the study of fossil shark teeth. Journal of Vertebrate Paleontology, 27(4): 798– 810. Randall, J. E. 1973. Size of the great white shark (Carcharodon). Science, 181, 169170.
57

Randall, J. E. 1987. Refutation of lengths of' 11.3, 9.0 and 6.4 m attributed to the white shark, Carcharodon carcharias. California Fish and Game, 73: 163168.
Reif, W.-E. 1976. Morphogenesis, pattern formation and function of the dentition of Heterodontus (Selachii). Zoomorphologie, 83: 1-47.
Reif, W.-E. 1980. Development of dentition and dermal skeleton in embryonic Scyliorhinus canicula. Journal of Morphology, 166: 275-288.
Reif, W.-E., McGill, D., and Motta, P. 1978. Tooth replacement rates of the sharks Triakis semifasciata and Ginglymostoma cirratum. Zoologische Jahrbücher Abteilung für Anatomie und Ontogenie der Tiere, 99: 151-156.
Rick, T. C., Erlandson, J. M., Glassow, M. A., and Moss, M. L. 2002. Evaluating the economic significance of sharks, skates, and rays (Elasmobranchs) in prehistoric economies. Journal of Archaeological Science, 29: 111-122.
Robinson, D. 2012. Under the Isles of Shoals. Portsmouth Marine Society, Portsmouth, New Hampshire.
Rosset, A., Spadola, L., and Ratib, O. 2004. OsiriX: an open-source software for navigating in multidimensional DICOM images. Journal of Digital Imaging, 17: 205-216.
Rygg, A. D., Cox, J. P. L., Abel, R., Webb, A. G., Smith, N. B., and Craven, B. A. 2013. A computational study of the hydrodynamics in the nasal region of a hammerhead shark (Sphyrna tudes): Implications for olfaction. PloS one, 8: e59783.
58

Santana-Morales, O., Sosa-Nishizaki, O., Escobedo-Olvera, M. A., Oñate-González, E. C., O'Sullivan, J. B., and Cartamil, D. 2012. Incidental catch and ecological observations of juvenile white sharks, Carcharodon carcharias, in western Baja California, Mexico: Conservation implications. In Global Perspectives on the Biology and Life History of the White Shark. M. L. Domeier, Ed., CRC Press, Boca Raton. 187-198.
Sawada, T. 2003. Ultrastructure of basement membranes in monkey and shark teeth at an early stage of development. Medical Electron Microscopy, 36: 204-212.
Sawada, T., and Inoue, S. 2003. Ultrastructure of basement membranes in developing shark tooth. Calcified tissue international, 72: 65-73.
Shimada, K. 2002a. Dental homologies in lamniform sharks (Chondrichthyes: Elasmobranchii). Journal of Morphology, 251: 38-72.
Shimada, K. 2002b. Teeth of embryos in lamniform sharks (Chondrichthyes: Elasmobranchii). Environmental Biology of Fishes, 63: 309-319.
Shimada, K. 2002c. The relationship between the tooth size and total body length in the shite shark, Carcharodon carcharias (Lamniformes: Lamnidae). Journal of Fossil Research, 35: 28-33.
Shimada, K. 2005. Phylogeny of lamniform sharks (Chondrichthyes: Elasmobranchii) and the contribution of dental characters to lamniform systematics. Paleontological Research, 9: 55–72.
Smith M. M., and Coates, M. I. 1998. Evolutionary origins of the vertebrate dentition: Phylogenetic patterns and developmental evolution. European Journal of Oral Science. 106: 482–500. (doi:10.1046/j.0909-8836.t01-4-.x)
59

Stevens, J. D. 1974. The occurrence and significance of tooth cuts on the blue shark (Prionace glauca L.) from British waters. Journal of the Marine Biological Association of the United Kingdom, 54: 373-378.
Tapanila, L., Pruitt, J., Pradel, A., Wilga, C. D., Ramsay, J. B., Schlader, R., and Didier, D. A. 2013. Jaws for a spiral-tooth whorl: CT images reveal novel adaptation and phylogeny in fossil Helicoprion. Biology Letters 9: 20130057. http://dx.doi.org/10.1098/rsbl.2013.0057. Pages 1-5
Thomasset, J.-J. 1930a. Recherches sur les tissus dentaires des poissons fossiles. Archives d'Anatomie, Histologie et Embryologie, 10: 5-153
Thomasset, J.-J. 1930b. La cavité pulpaire des dents des squales. Comptes Rendus du Congrès de l'Association Française pour l'Avancement des Sciences, La Rochelle 1928. 401-403.
Vélez-Zuazo, X., and Agnarsson, I. 2011. Shark tales: a molecular species-level phylogeny of sharks (Selachimorpha, Chondrichthyes). Molecular Phylogenetics and Evolution, 58: 207-217.
Whitenack, L. B. 2008. The biomechanics and evolution of shark teeth. Ph.D. dissertation, University of South Florida. 354 pp.
Whitenack, L. B. and Gottfried, M. D. 2010. A morphometric approach for addressing tooth-based species delimitation in fossil mako sharks, Isurus (Elasmobranchii: Lamniformes). Journal of Vertebrate Paleontology, 30:17-25.
Whitenack, L. B., Simkins, D. C., Motta, P. J., Hirai, M., and Kumar, A. 2010. Young's modulus and hardness of shark tooth biomaterials. Archives of oral biology, 55: 203-209.
60

Wilga, C. D. 2005. Morphology and evolution of the jaw suspension in lamniform sharks. Journal of Morphology, 265: 102-119.
Wroe, S., Huber, D. R., Lowry, M., McHenry, C., Moreno K., Clausen, P., Ferrara, T. L., Cunningham, E., Dean, M. N., and Summers, A. P. 2008. Threedimensional computer analysis of white shark jaw mechanics: How hard can a great white bite? Journal of Zoology, 276: 336-342.
Zangerl, R. 1981. Handbook of Paleoichthyology, Vol. 3A. Chondrichthyes I (Paleozoic Elasmobranchii). Gustav Fischer, Stuttgart.
Zangerl, R., Winter, H. F., and Hansen, M. C. 1993. Comparative microscopic dental anatomy in the Petalodontida (Chondrichthyes, Elasmobranchii). Fieldiana. No. 26. Field Museum of Natural History.
61

FIGURE LIST AND CAPTIONS Fig. 1. Phylogenetic relationships of the five living species of lamnids based on
Naylor et al. (1997). Figures of sharks from Castro (1983) used with permission. Fig. 2. Numbering scheme for tooth loci used by Applegate and Espinosa-Arrubarrena (1996: Fig.1A). This scheme interprets the first two loci in the upper jaw as homologs of the first and third loci in other Lamniformes and recognizes two upper anterior teeth, one upper intermediate tooth, five upper lateral teeth and four upper posterior teeth. In this scheme, the lower jaw has three anterior teeth, five lateral teeth, and three posterior teeth. Fig. 3. Interpretation of homologies of tooth loci in extant Lamnidae modified from Shimada (2005: Fig. 4); images of tooth sets based on Compagno (2011). In this scheme, the dentition of the upper jaw consists of two anterior teeth (A), one intermediate tooth (I), and ten lateral teeth (L) whereas the lower jaw has two anterior teeth (a), one intermediate tooth (i) and nine lateral teeth (l). Unlabeled posterior teeth are present in the upper and lower jaws of both species of Lamna and in the lower jaw of Isurus oxyrinchus. Fig. 4. Model for tooth replacement in elasmobranchs modified from Reif (1976). During early development, the dental lamina extends inward on the lingual side of the jaw. New tooth germs form by epithelial-mesenchymal interactions in primordial tissue at the base of the dental lamina. Enameloid caps are first to form. Roots initially form in replacement teeth as a meshwork of trabecular
62

dentine that subsequently mineralizes to form osteodentine typical of functional teeth. Fig. 5. 3-D model rendered from CT scan of PL3 tooth of an adult great white shark (NMFS F1). (A) Labial view showing crown measurements. (B) Lingual view showing external features of teeth. Scale bar = 5 mm. Fig. 6. Method for estimating crown inclination. Fig. 7. Crown height as a function of TL for great white shark specimens studied by Randall (1973) with new data reported here (red circles). Yellow stars indicated specimens studied here that lack TL data; their placement on the regression line is by eye and for reference only. Specimens CT-scanned for this study are indicated. Fig. 8. Lateral view of head of juvenile great white shark (MCZ 36470). (A) CTreconstruction of jaws and chondrocranium. (B) Schematic line drawing to show arrangement of teeth and positions of dental bullae and tooth wells. Scale bars = 5 cm. Fig. 9. Functional teeth in a preserved juvenile great white shark (MCZ 36470). (A) Left side showing the first functional teeth of the upper (F1) and lower jaws (f1). (B) Right side with skin and muscle removed. Two functional teeth, f1 and f2, in tooth files of the lower jaw can be seen. Scale bars = 5 cm. Fig. 10. Oblique view of right side of MNZ P.052022 to show functional teeth in the lower jaw. Note the three fully erupted mr1 functional teeth. Only two functional teeth are erupted in more distal files mr2-mr5. Scale bars = 5 cm.
63

Fig. 11. Jaws of an adult great white shark (AMNH 53095) to show general terminology for dentition and tooth files. Scale bar = 2 cm.
Fig. 12. 3-D model of upper jaw rendered from CT scan of the head of a juvenile great white shark (MCZ 36470) to show dental bullae and tooth wells. Scale bar = 5 cm
Fig. 13. Plots of crown width, crown height, CW:CH, and crown inclination for AMNH 53095. Measurements of the left and right teeth at each locus were averaged. (A) Width of crowns in the upper jaw. (B) Height of crowns in the upper jaw. (C) CW:CH in upper jaw. (D) Crown inclination in the upper jaw. (E) Width of crowns in the lower jaw. (F) Height of crowns in the lower jaw. (G) CW:CH in lower jaw. (H) Crown inclination in the lower jaw.
Fig. 14. Box and whisker plots showing CW:CH and variation for the functional tooth of the first 11 tooth files. (A) Tooth files of palatoquadrate. (B) Tooth files of Meckel’s cartilage.
Fig. 15. Tooth from lateral zone of a juvenile great white shark to show difference between serrations and lateral cusplets. (A) Labial surface. (B) Lingual surface. Scale bar = 5 mm.
Fig. 16. Dried jaws of a subadult great white shark (NMFS 12). Scale bar = 30 mm. Fig. 17. Photographs of individual teeth of an adult great white shark (NMFS F1). (A)
Labial surface of PR2. (B) Lingual surface of the same tooth. (C) Labial surface of mr4. (D) Lingual surface of the same tooth. Scale bars = 5 mm. Fig. 18. 3-D models rendered from CT scans of individual teeth of an adult great white shark (NMFS F1). (A) Labial surface of PR3. (B) Lingual surface of the same
64

tooth. (C) Labial surface of mr2. (D) Lingual surface of the same tooth. Scale bars = 5 mm. Fig. 19. 3-D model rendered from CT scans of an individual tooth (ml1) of a juvenile great white shark (NMFS 5). The tip of the crown curves labially; such curvature is more pronounced in juvenile specimens. Note the tiny serrations and the lateral cusplet visible near the root. Scale bar = 5 mm. Fig. 20. Views of anterior teeth of lower jaw. (A) Photograph of the symphysial region of the dried lower jaw of a juvenile great white shark (NMFS 3) showing the dental bullae lateral to the mandibular symphysis. (B) 3-D models rendered from CT scans of mr1 tooth file in a juvenile white shark (NMFS 4) illustrating curvature of the file to conform to the shape of the dental bulla. The presence of cusplets on these teeth is characteristic of juveniles. Scale bars = 5 mm. Fig. 21. 3-D models rendered from CT scans of tooth files of a juvenile great white shark (NMFS 4; same specimen as in Figs. 22, 23 and 24). (A) PR1 tooth file showing two functional teeth (F1, F2), two replacement teeth (R1, R2), and four developing teeth (D1-D4). (B) mr1 tooth file showing two functional teeth (f1, f2), two replacement teeth (r1, r2), and four developing teeth (d1-d4). Scale bars = 5 mm. Fig. 22. Sagittal 2-D radiographs of tooth files from a juvenile great white shark (NMFS 4; same specimen as in Figs. 21, 23 and 24). (A) PR1 file. (B) mr1 file. Note mineralization of trabecular dentine in later stages of development. Scale bars = 5 mm.
65

Fig. 23. Serial sagittal 2-D radiographs of mr1 tooth file in a juvenile white shark (NMFS 4; same specimen as in Figs. 21, 22, and 24). Parts (A) through (D) present sections approximately 1.5 mm thick. Nutritive pores for vascular connections are visible on lingual and labial sides of replacement teeth and the second functional tooth. Vascular connections on the labial face have been lost in the first functional tooth. Note also the appearance and mineralization of the trabecular dentine. Scale bars = 5 mm.
Fig. 24. Serial sagittal 2-D radiographs of mr1 tooth file in a juvenile white shark (NMFS 4; same specimen as in Figs. 21, 22, and 23). Scale bars = 5 mm.
Fig. 25. 3-D models rendered from CT scans of mr1 tooth files. (A) mr1 tooth file of a juvenile mako shark, Isurus oxyrinchus (CUMV 97455) showing three erupted, fully formed functional teeth (f1-f3). (B) mr1 tooth file of a juvenile great white shark (NMFS 8) showing one fully erupted functional tooth (f1) and one fully formed, partially erupted functional tooth (f2). Scale bars = 5 mm.
Fig. 26. Sectioned 3-D model rendered from CT scans of mr1 tooth files. (A) mr1 tooth file of a juvenile mako shark (CUMV 97455) showing three erupted, fully formed functional teeth, f1-f3. (B) mr1 tooth file of a juvenile great white shark (NMFS 5) showing two functional teeth, f1 and f2. Although partially erupted, incomplete mineralization of the root of r1 indicates that it is not yet a functional tooth. Scale bars = 5 mm.
Fig. 27. Sliced 3-D model rendered from CT scans to show two histotypes of shark teeth. (A) Fully developed tooth of a subadult great white shark tooth (PL3;
66

NMFS F1) exhibits osteodont histotype, which is evident by the lack of a pulp cavity. (B) Fully developed tooth of an adult bull shark, Carcharhinus leucas (PL; CUMV 97581) exhibits orthodont histotype. Note the large pulp cavity. Scale bars = 5 mm. Fig. 28. Broken developing tooth (ml1d2) from MCZ 153575. The enameloid and orthodentine crown (left) is easily separated from the osteodentine (right). Scale bar = 5 mm. Fig. 29. Sagittally sectioned 3-D model rendered from CT scans of tooth files of a juvenile great white shark (NMFS 4) to show a 3-D summary of stages in tooth replacement. (A) UR1 tooth file. (B) lr1 tooth file. Functional (F or f), replacement (R or r), and developing (D or d) teeth are labeled and numbered. Scale bars = 5 mm. Fig. 30. 3-D models comparing development of lateral cusplets in Lamna to serrational cusplets in Carcharodon. (A) mr3 through mr6 tooth files of Lamna nasus (CUMV 97646). (B) mr2 tooth files of Carcharodon carcharias (NMFS 5). (C) mr2 tooth files of Carcharodon carcharias (NMFS 4). Scale bars = 5 mm. Fig. 31. 3-D models comparing tooth replacement and tooth morphology in Lamna, Isurus and Carcharodon. Note, jaw sections and teeth have been scaled to the same approximate size for ease of comparison. Fig. 32. 3-D models and sectioned 3-D model rendered from CT scans of an isolated replacement tooth of Carcharodon carcharias from an archaeological study of Smuttynose Island, Maine. (A) Lingual view of tooth. Serrations and the base
67

of the enameloid are labeled. (B) Labial view of tooth. (C) Lateral view of tooth. (D) Lingual view of tooth sectioned to show interior of crown. Enameloid, orthodentine, and osteodentine layers are labeled. Fig. 33. 3-D models and sectioned 3-D models rendered from CT scans of an isolated tooth of Lamna nasus from an archaeological study of Smuttynose Island, Maine. (A) Lingual view of tooth. The base of the enameloid and protruding osteodentine core are labeled. (B) Labial view of tooth (C) Lateral view of tooth (D) Lingual view of tooth sectioned to show interior of crown. Enameloid, orthodentine, and osteodentine layers are labeled. Fig. 34. Set of teeth from the left upper and lower jaws of an adult great white shark (GHC F7687). The crowns of these teeth are disproportionately narrow compared to other great white shark specimens. Scale bar = 2 cm. Fig. 35. History of terminology for dentine and enameloid in shark teeth.
68

Table 1. Measurements of palatoquadrate teeth (mm).

PL1 PL2 PL3 PL4

PL5

PL6

PL7

PL8

PL9

PL10

PL11

CW CH CW CH CW CH CW CH CW CH

CW CH CW CH CW CH CW CH CW CH CW CH

NMFS F1

25.0 27.5 21.1 26.5 23.1 24.0 25.5 22.0 24.5 23.1 24.0 23.0 22.8 20.0 18.0 16.2 15.5 13.2 13.0 10.5 11.5 9.0

NMFS F2

N/A N/A N/A N/A 21.0 23.0 N/A N/A N/A N/A N/A N/A 25.0 18.5 17.0 16.3 14.5 12.0 N/A N/A N/A N/A

NMFS 11

19.2 21.3 N/A N/A 17.5 14.0 21.8 18.5 N/A N/A 21.3 18.8 N/A N/A 18.6 15.6 14.6 10.8 11.3 7.9 7.2 3.4

NMFS 12

15.1 16.5 15.2 15.9 14.7 11.1 16.5 14.0 17.2 14.4 15.4 14.1 14.1 11.7 11.0 9.2 9.1 6.7 7.3 4.0 4.8 3.3

AMNH 53095

20.5 28.5 21.0 29.3 18.7 21.7 20.4 25.0 22.0 28.9 20.6 25.3 17.7 22.8 15.0 16.3 12.3 12.4 9.0 8.6 6.6 5.3

ANSP 69984

N/A N/A 32.6 38.6 34.6 25.2 28.9 31.1 N/A N/A N/A N/A 26.3 25.4 19.7 17.6 15.3 11.7 11.7 7.9 9.4 6.1

FLMNH SOP 020105018.011 15.6 19.7 16.6 19.1 15.3 16.0 17.5 17.4 16.1 18.3 16.4 17.1 13.8 12.9 11.1 10.0 9.3 7.8 7.1 5.4 5.4 4.4

FLMNH SOP 29905026.023 14.0 21.3 15.1 20.3 N/A N/A 16.0 15.5 16.2 17.3 15.4 15.9 10.9 13.1 8.4 10.1 5.9 6.6 N/A N/A N/A N/A

FLMNH UF 48285

17.1 23.9 18.2 25.5 17.5 17.3 19.1 17.2 20.0 17.7 18.6 18.1 17.5 15.5 14.4 11.2 10.9 6.8 7.8 4.7 5.1 3.5

GH 0601997

31.1 41.0 31.8 43.0 28.7 27.9 31.7 32.3 30.7 35.9 26.8 35.1 20.2 25.5 30.9 15.7 15.5 10.5 10.9 7.7 8.1 6.7

GH 09101981

17.2 24.8 19.5 24.9 17.7 17.0 19.7 19.1 19.3 19.4 19.1 19.1 15.7 15.2 20.3 11.7 10.5 7.7 7.6 5.3 5.9 5.8

GH 21091985

42.7 54.2 43.3 52.3 37.0 32.5 42.4 39.2 42.1 43,39 39.9 40.8 35.6 37.3 39.8 20.2 22.5 13.6 13.2 8.9 12.1 8.1

GH F11582

37.2 47.8 37.8 46.4 31.7 31.0 N/A N/A 36.4 35.7 35.9 34.6 33.4 27.0 26.4 16.9 18.7 17.4 14.6 9.2 N/A N/A

GH F7687

34.9 51.0 37.0 50.4 32.6 36.2 39.2 41.3 39.4 47.8 36.0 42.6 30.1 32.2 24.4 22.8 19.5 14.1 15.0 9.6 10.0 7.8

GH H8993

37.9 44.6 38.3 40.5 32.5 34.5 35.9 29.4 36.9 34.5 36.7 35.6 32.2 28.0 25.3 19.2 19.6 12.6 16.4 9.4 11.1 8.2

GH F12484

25.7 35.6 28.3 36.8 25.3 30.2 28.9 29.4 28.4 29.6 27.1 27.4 23.4 22.4 18.0 15.6 14.1 9.2 9.9 6.6 7.4 4.1

GH 06111985

41.8 52.5 43.1 50.7 34.5 33.2 40.6 40.9 41.4 43.4 40.1 41.3 36.5 33.1 29.2 21.4 22.8 14.1 16.3 9.7 11.8 6.8

GH 03011994

38.5 46.1 37.7 48.3 36.9 38.4 39.6 38.4 40.0 41.1 38.5 37.6 34.5 29.2 27.8 21.9 20.9 14.8 15.7 11.8 11.2 7.2

GH 22031984

36.5 49.9 36.5 51.0 30.8 36.9 37.8 38.4 36.7 39.2 34.6 36.0 31.9 28.9 24.1 18.3 18.6 13.0 12.9 10.0 9.5 6.1

GH 23041992

24.4 33.7 25.1 35.7 24.3 26.0 28.4 32.8 26.9 32.9 26.2 30.3 22.5 24.8 14.9 16.0 13.5 12.8 9.7 9.3 7.9 6.0

Table 2. Measurements of Meckelian teeth (mm).

ml1

ml2

ml3

ml4

ml5

ml6

ml7

ml8

ml9

ml10

ml11

CW CH CW CH CW CH CW CH CW CH CW CH CW CH CW CH CW CH CW CH CW CH

NMFS F1

N/A N/A N/A N/A 18.0 20.0 19.5 19.5 20.0 18.5 19.0 17.6 N/A N/A 14.0 10.4 N/A N/A N/A N/A N/A N/A

NMFS F2

18.0 24.0 21.1 23.5 19.1 21.0 18.2 20.0 18.0 18.5 18.5 15.4 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A

NMFS 11

13.8 N/A 17.8 19.6 15.5 N/A N/A N/A 15.3 N/A 14.1 N/A 12.5 9.4 9.6 6.6 7.2 4.5 4.3 2.5 3.8 1.8

NMFS 12

11.9 N/A 12.6 N/A 12.5 N/A 11.4 10.4 11.3 N/A 10.5 9.6 9.1 8.0 7.9 5.8 6.2 N/A 3.0 1.9 N/A N/A

AMNH 53095

15.5 22.1 17.3 22.3 15.7 17.8 16.0 17.3 14.2 17.3 11.9 13.7 11.5 10.8 9.7 7.1 7.7 5.3 5.0 3.4 3.6 2.7

ANSP 69984

20.6 30.2 N/A N/A N/A N/A N/A N/A 22.4 26.3 19.4 19.6 14.9 15.5 12.9 11.0 N/A 9.2 7.2 4.8 N/A N/A

FLMNH SOP 020105018.011 12.2 19.0 14.4 20.0 N/A N/A N/A N/A 12.7 13.5 10.1 12.0 8.4 10.5 6.9 7.9 5.4 6.0 3.9 3.2 N/A N/A

FLMNH SOP 29905026.023 N/A N/A 12.2 18.0 10.6 14.4 11.4 13.2 10.8 12.2 9.9 10.9 8.0 8.6 N/A N/A 5.6 4.0 N/A N/A N/A N/A

FLMNH UF 48285

N/A N/A N/A N/A N/A N/A 14.0 16.1 14.1 14.8 N/A N/A 10.7 12.0 9.5 9.3 7.0 6.2 N/A N/A N/A N/A

GH 0601997

22.2 34.4 24.6 38.3 21.9 29.8 22.8 28.9 20.8 25.1 18.7 20.6 16.0 14.7 13.9 10.6 9.1 7.0 6.7 4.8 4.4 2.9

GH 09101981

12.3 20.0 13.4 20.6 12.3 17.6 12.8 15.4 12.9 14.9 11.6 13.2 10.2 11.3 8.5 8.1 5.5 5.8 3.9 3.2 N/A N/A

GH 21091985

26.1 36.0 29.4 39.8 26.5 35.5 26.3 30.6 26.4 29.0 19.8 21.4 24.6 16.9 20.7 11.1 17.9 7.2 12.2 4.6 8.9 3.5

GH F11582

N/A N/A 25.7 38.5 25.1 33.1 26.1 31.6 23.2 29.9 20.8 24.0 17.2 18.3 15.7 13.1 14.0 9.4 9.0 5.9 5.8 3.9

GH F7687

22.4 37.3 28.2 41.4 26.4 33.5 26.6 32.6 23.1 29.8 20.8 25.4 15.1 19.6 14.5 12.6 11.4 8.1 6.3 3.7 6.3 3.5

GH H8993

25.3 39.4 29.4 42.2 25.8 35.7 24.4 31.5 23.4 26.8 20.1 22.3 16.1 16.8 14.9 12.7 11.3 8.7 6.7 4.6 4.6 3.0

GH F12484

17.7 29.3 21.6 29.9 16.9 24.1 19.7 22.6 16.7 20.0 14.4 16.5 12.4 12.2 10.2 9.6 8.6 6.7 5.6 4.3 N/A N/A

GH 06111985

27.9 34.9 32.3 37.6 26.4 33.7 25.4 31.1 27.9 29.3 26.4 23.0 22.7 20.2 20.7 13.9 17.2 8.5 12.2 5.6 8.0 3.3

GH 03011994

25.4 40.9 29.1 42.9 27.3 38.7 29.3 36.8 26.7 33.5 23.8 28.8 19.2 20.5 16.1 15.1 11.9 9.3 8.9 5.4 4.9 2.9

GH 22031984

21.3 36.6 25.9 41.3 22.7 35.9 22.4 31.3 21.3 28.5 19.1 21.7 17.8 16.9 15.0 12.7 11.1 8.0 8.7 5.6 6.2 3.3

GH 23041992

18.6 26.3 20.5 29.5 18.4 24.4 19.6 23.0 18.3 22.0 16.2 19.1 13.9 19.1 11.8 10.1 9.0 6.7 5.8 3.8 3.7 2.2

Lamnidae

Porbeagle Lamna nasus
Salmon shark Lamna ditropus
Short n mako Isurus oxyrinchus
Long n mako Isurus paucus
Great white shark Carcharodon carcharias
Figure 1

Figure 2

Upper Teeth
A1 A2 I1 L1 L2 L3 L4 L5 L6 L7 L8 L9 L10

Lower Teeth

a1

a2

i1 l1

l2 l3

l4 l5 l6 l7 l8 l9

A. Lamna nasus
A1 A2 I1 L1 L2 L3 L4 L5 L6 L7 L8 L9 L10

a1 a2 i1 l1 l2 l3 l4 l5 l6 l7 l8 l9

B. Lamna ditropis
A1 A2 I1 L1 L2 L3 L4 L5 L6 L7 L8 L9 L10

a1 a2

i1

l1

l2 l3 l4 l5 l6 l7 l8 l9

C. Isurus oxyrinchus
A1 A2 I1 L1

L2

L3 L4 L5 L6 L7 L8 L9 L10

a1 a2

i1

l1

l2 l3 l4 l5 l6 l7 l8 l9

D. Isurus paucus
A1 A2 I1 L1 L2 L3 L4 L5 L6 L7L8 L9 L10

a1 a2 i1 l1 l2 l3 l4 l5 l6 l7 l8 l9

E. Carcharodon carcharias Figure 3

Enameloid cap

Osteodentine

AC

1

Inward growth of dental lamina

Primordial tissue B

1 Inward growth of dental lamina
2

Oral ectoderm/ dental lamina

Primordial tissue
Mesenchyme

Figure 4

1 2 3 4 5
Meckel’s cartilage

D
Inward growth of dental lamina
Primordial tissue Enameloid cap

1

2 3
4

Direction of tooth eruption and replacement

5 6
Incompletely mineralized osteodentine

Primordial tissue
WEB
Completely mineralized osteodentine

A CH
Figure 5

CW B

Dorsal Mesial
Labial

Less dense

More dense

NP SR

RT TN
CRN Dorsal
Distal Lingual

Less dense

More dense

ML DL CH
CW ML/DL < 1.0 Crown points mesially
Figure 6

ML DL CH
CW ML/DL = 1.0 Crown symmetrical

ML CH

DL

CW ML/DL > 1.0 Crown points distally

CH, mm

60 Data replotted from Randall (1973)
55 New specimens with TL and CH data 50 New specimens with CH data only
45

40

35

30 NMFS F1 (single teeth scanned)

25 NMFS F2 (single teeth scanned)

AMNH 53095 (jaw scanned)

20 MCZ 36470 (whole head scanned)

NMFS 12 (jaw scanned)

15

Smallest free-living specimens (Casey and Pratt, 1985)

NMFS 11 (jaw scanned)

10 NMFS 4 (jaw scanned)

5 NMFS 8 (jaw scanned)

r2(red & black data points) = 0.952 Y = 9.0215•X + 0.3489

0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

Figure 7

Juveniles

Subadults Total length, m

Adults

6.0

A

B

RC
OP DB

C P

TW DB

TW

H QP AP CH
M

Chondrocranium
Figure 8

Palatoquadrate and Meckel’s cartilage

Gum tissue and dental ligament

Enameloid cap

Osteodentine

A

PL3 PL4

PL2

PL1

PR1

ml3 ml2

ml1

ml4

PL5 ml5

ml6

B

Figure 9

mr5f2 mr5f1 (broken)

mr4f2 (broken) mr3f2 (erupting)

mr2f2

mr4f1 (broken)

mr3f1

mr2f1

mr1f3

ml1f3

mr1f2

MS

mr1f1

ml1f2 ml1f1

Figure 10

Upper Right Quadrant
lower right quadrant
Figure 11

PS Upper Left Quadrant

PL1 PL2 PL3 PL4
PL5 PL6
PL7 PL8 PL9 PL10 PL11
MQJ
ml11 ml10 ml9 ml8 ml7
ml6 ml5 ml2 ml3 ml4 ml1

LQJ

MS lower left quadrant

DB DB

TW TW Anterior

Figure 12

Right
Ventral Posterior

Left

A. 30
25

CW CH

Tooth Dimensions, mm

20

15

10

5

0 P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 Tooth locus

C.

CW:CH

1.5
1.0
0.5
0.0 P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 Tooth locus
E. 1.5
1.0 ML/DL < 1.0
0.5 Crown points mesially
0.0 P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 Tooth locus
Figure 13

ML/DL

B. 25

CW CH

Tooth Dimensions, mm

20

15

10

5

0 m1 m2 m3 m4 m5 m6 m7 m8 m9 m10 m11 Tooth locus

D. 2.0

1.5

CW:CH

1.0

0.5

0.0 m1 m2 m3 m4 m5 m6 m7 m8 m9 m10 m11 Tooth locus

F. 1.5

ML/DL

1.0 ML/DL < 1.0
0.5 Crown points mesially

0.0 m1 m2 m3 m4 m5 m6 m7 m8 m9 m10 m11
Tooth locus

CW:CH CW:CH

A. 2.5
2.0
1.5
1.0
0.5
0.0 P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 Tooth locus
Figure 14

B. 2.5
2.0
1.5
1.0
0.5
0.0 m1 m2 m3 m4 m5 m6 m7 m8 m9 m10 m11 Tooth locus

A
CRN SR
CPT

Dorsal

B

Distal

Labial SR
CPT

CRN

SR CPT

Dorsal Mesial
Lingual
SR CPT

RT RNA
RTL
Figure 15

RT RTL

NP

Upper Right Quadrant

Upper Left Quadrant
PL1 PL2 PL3 PL4 PL5 PL6 PL7 PL8 PL9 PL10 PL11

lower right quadrant
Figure 16

ml11 ml10 ml9 ml8 ml7
ml6
ml5 ml4 ml3 mr1 ml1 ml2
lower left quadrant

A RT

CRN

SR

C

CRN

SR

RT
Figure 17

B
RTL TN

NP RTL
TN

Dorsal Distal
Labial

Dorsal

D

Distal

Labial

TN RTL

Dorsal SR
Mesial
Lingual

SR NP

Dorsal Mesial
Lingual
TN RTL

A RT

RNA

B
RTL TN

NP RTL
TN

CRN

SR

Dorsal Distal
Labial

C

CRN

SR

RT RNA

Figure 18

Less dense

More dense

D

Dorsal Distal
Labial

TN

RTL

Less dense

More dense

SR SR

Dorsal Mesial
Lingual

Less dense

More dense

Dorsal Mesial
Lingual
TN

NP RTL

Less dense

More dense

CRN

SR

CPT RT

Figure 19

Recurvature of tooth

TN LB

Dorsal

Labial

Lingual

RTL

Ventral

A

mr5 mr4

LDB

ml5 ml4

mr3

mr2 mr1

ml1

ml3 ml2

B Lingual

mr1d3 mr1d2 mr1d1 mr1r2 mr1r1

Distal

Mesial

mr1f2

Labial

CPT
Figure 20

mr1f1

A
PR11D2 PR1D1 PR1R2
PR1R1

Dorsal

Labial

Lingual

PR1F1

Ventral

B mr1f1

Dorsal

Labial mr1f2

Lingual

Ventral
mr1r1 mr1r2 mr1d1 mr1d2 mr1d3 mr1d4

Figure 21

A P

PR1D1 PR1R2
PR1R1

DB

NP VC

Dorsal

Labial

Lingual

PR1F1

Ventral

B mr1f2

Dorsal

Labial

Lingual

mr1r1

mr1r2

Ventral

f1 mr1d1

VC NP

M

mr1d2 DB

Figure 22

A OD NP

Dorsal

B

Labial

Lingual

OD EN

Ventral

VC M

DB

C OD

Dorsal

D

Labial

Lingual

OD EN

Ventral

OD EN

M

Figure 23

NP NP

Dorsal

Labial

Lingual

Ventral

EN

M

Dorsal

Labial

Lingual

OD OD

SR

Ventral

OD

EN M

A M

EN DB
OD

B M
NP

EN
OD DB

NP VC
OD

Dorsal

Labial

Lingual

NP

OD VC

Dorsal

Labial

Lingual

Ventral

Ventral

CD

M
Figure 24

EN OD
DB
VC

Dorsal

Labial

Lingual

Ventral

M NP

EN
DB OD

Dorsal

Labial

Lingual

Ventral

A mr1f1

mr1f2

M PLS

Dorsal

B

Labial

Lingual

mr1f1

mr1f3 Ventral mr1r1 mr1d1

M

Dorsal

Labial

Lingual

mr1f2

Ventral
mr1r1 mr1r2
mr1d1 dmr12 mr1d3

Figure 25

A mr1f1

mr1f2

M

Dorsal

B

Labial

Lingual

mr1f3

Ventral

mr1r1

mr1d1

mr1f1

mr1f2 M

Dorsal

Labial

Lingual

mr1r1 Ventral

mr1r2

mr1d1 mr1d2

mr1d3

Figure 26
.

A RT

CRN

VC

SR

C

B NP NP
RT
OD

OD Dorsal

OR EN

Mesial Labial

CRN

PC SR

Less dense

More dense

D

Dorsal OR Mesial EN Labial

Less dense

More dense

EN OR OR

EN OR PC

Figure 27

Lingual Mesial
Dorsal

Lingual Mesial
Dorsal

SR EN
BE

OD

Figure 28

A PR1D2
PR1D1 PR1R2
PR1R1

Dorsal

Labial

Lingual

PR1F1

Ventral

B mr1f1

Dorsal

mr1f2 Labial

Lingual

Ventral mr1r1
mr1r2
mr1d1 mr1d2 mr1d3 mr1d4

Figure 29

A B Figure 30

LC
C
CPT CPT
CPT CPT
Dorsal Mesial
Lingual

LC LC LC LC
Dorsal LC
Mesial Lingual
CPT CPT
CPT CPT
Dorsal Mesial
Lingual

Lamna
Isurus
Carcharodon
Figure 31

A BE

BE

SR

Dorsal

B

Distal

Lingual

Dorsal BE
Mesial
Labial
SR

C Dorsal D

BE BE

Labial

SR

Figure 32

Dorsal Distal
Lingual
OD OR E

AB Dorsal
Lingual

BE OD

C

Dorsal

D

Labial

Figure 33

BE

Dorsal Labial
BE OD
Dorsal Lingual E OR OD

P3 P1 P2
m1 m2

P4 P5

P6

m3 m4

m6 m5

P7 P8 P9 P10 P11 P12 P13
m11 m7 m8 m9 m10

Figure 34

Figure 35

A. Thomasset (1930). cp, pulp cavity; f, fibrodentine and enamel; o, osteodentine; p, pseudodentine

B. Bertin (1958). a, enamel or vitrodentine; b, orthodentine; c, pseudodentine; d, osteodentine (noted in text but not indicated on this figure)

C. Cappetta (2012): Enl, enameloid; Or, orthodentine; Puc, pulp cavity; Trb, trabecular dentine

En En Or Or
Puc Os
Os

D. Modified from Whitenack et al. (2010): Enl, enameloid; Or, orthodentine; Os, osteodentine; Puc, pulp cavity

E. Zangerl et al. (1993): b, base; c, crown; dt, dentine tubule; o, orthodentine; pc, pulp cavity; pcr, pulp cavity remnant; td, trabecular dentine; v, vitrodentine; vt, vertical vascular tube